When Austin Estes took his sick infant son to urgent care, he struggled to change his diaper in an exam room not equipped with a changing table. “Oh, if only Mom was here,” the nurse said. Estes, an education-policy consultant in Washington, D.C., wondered why she’d think his wife would better handle an impossible diaper change.

Justin Rauzon, a project director in Los Angeles, told me he listed himself as the primary contact on the intake paperwork at his child’s pediatrician’s office. But the office staff frequently ignores that information. “They usually reach out to my wife, who either tries to handle things (sometimes without the full context), patches me into the conversation, or tells them to call me,” he told me in an email. “Exactly the sort of inefficient experience we want to avoid by listing me to call first.”

Shannon Carpenter, who has written a book (and for The Atlantic) about being a stay-at-home dad, called his daughter’s high school one day to let them know she was staying home sick. The school immediately contacted his wife to confirm that she really was ill. Years ago, he picked his son up from day care and another child asked why the boy was always picked up by his dad. “He has a daddy-mommy,” the teacher said. (“The fuck?” Carpenter thought.)

Schools, pediatricians, random passersby—so many people assume that Mom knows what’s going on with the family, and that Dad does not. If a child has a problem, they think, the first step is to contact the mother—no matter where she is or what she might be doing. Yevgeniya Nusinovich, a mom of four, told me that earlier this year, a doctor’s office called her three times while she was in Taiwan for work, leaving messages for her in the middle of the night without ever trying to reach her husband. When Alexis Miller took an international flight with her husband and their 11-month-old daughter, they booked two seats together and one a few rows back. Her husband took the first shift with the baby, who started fussing. The flight attendant walked past Miller’s husband and approached Miller to tell her to go help her baby calm down. Miller told her, “She is with her dad and she’ll settle in a minute.”

Read: A grand experiment in parenthood and friendship

I’m familiar with this phenomenon myself: I once got a call to confirm my son’s physical-therapy appointment, told the office to call my husband instead, and gave them his number. I hung up. They called me right back.

This isn’t just in our heads. Research backs up the idea that people tend to assume mothers are the default parent, even when they explicitly ask not to be. A few years ago, Kristy Buzard, an economist at Syracuse University, and her colleagues posed as fictitious parents and emailed more than 80,000 school principals, saying they were searching for a school for their child and asking for a call back. The researchers found that the principals were 40 percent more likely to call the pretend mothers back than the pretend fathers. Even in cases where the email came from the father, and the father said he was more available than his wife, the principals called the mother 12 percent of the time.

Part of the reason, Buzard posited, is “this underlying belief that moms are more available and are going to be more responsive.” That suspicion was underscored by the fact that in areas with more Republican-voting, religious, and rural people—traits she and her co-authors used as a proxy for traditional gender norms—moms were even more likely to be called. Katy Milkman, a behavioral economist at the University of Pennsylvania, told me, “We have a stereotype of the mother as the caregiver.” Many school administrators and doctor’s-office staffers, she said, “probably are not going through a deliberate thought process where they’re like, Huh, which of these two people should I call? Let me think about the probabilities of which of them is the caregiver.” She told me that “people jump to conclusions, maybe without even realizing it.”

Another explanation is that many kid-related institutions rely on software that’s janky and outdated. “The data systems aren’t smart enough to prioritize who gets called first,” Jen Shu, a pediatrician based in Atlanta, told me. “I never know on any given day which one I’m supposed to call, because our system isn’t smart enough to say, ‘For today, call this parent at this number.’” The software, she said, can sometimes have only one email on file, and can text only the parent whose cell is listed as the main number. If a mom brings in a newborn for an appointment and fills out the intake paperwork and then goes back to work while her husband is on paternity leave, a reliable way doesn’t always exist to notify the office that it should now contact the father. If the mother tells the receptionist, that person might not be the one whose job it is to update the patient’s chart. If she tries to make the change herself online, the patient portal might not feed the new information into the doctor’s records. “In this day and age,” Shu said, “it should be easier.”

Read: The isolation of intensive parenting

Of course, in many families, mothers are the primary contact. (Dustin Strickland, the assistant principal of North Murray High School in Georgia, told me that, based on a glance at his records, most families list the mom first.) Nevertheless, treating mothers as the default parent when they don’t want to be can add annoyingness to their already annoyance-filled lives. Unwanted calls from school or the doctor’s office can interrupt their focus at work, and passing the call on to Dad isn’t always as easy as it might seem. In another survey of parents that Buzard and her co-authors also conducted, mothers were 30 percent more likely than fathers to say that outsourcing a job to their partner is “disruptive to their day and that they still have to be involved in the task even after asking their partner for help,” a sentence that was surprisingly not followed by an upside-down smiling emoji. Some mothers get so fed up with the stress of being the one to field emails about flu shots and spirit-day outfits that they scale back at the office or stop working altogether. Buzard and her co-authors found that kid-related disruptions contributed to many women’s decisions to take lower-demand jobs that offered greater flexibility, or to to be a stay-at-home parent.

For dads, getting treated as the backup parent creates its own frustrations. Rauzon keeps track of his son’s asthma-medication regimen, and when the doctor’s office calls his wife instead of him, managing his medications and treatments becomes harder. Similarly, when the day care that Estes and his wife use calls his wife at the office when their son is sick, even though Estes works from home, “it adds an extra unnecessary step,” he told me. “I think people sometimes assume dads are just there for decoration.”

These days, many dads want to step up, and the family runs better when they do. If only everyone else would catch on and let them.