Not sure of the ages of your children, but as a 52yo who grew up in the States, I averaged 2-3 hours of homework a night in grade school. They'd tell us "oh, it's only about 15-20 minutes per class" which doesn't sound terrible, except that it was more like 20-30 minutes of work x 4-6 classes. By 7th grade I burned out and realized that the world didn't end if I started skipping homework, and my test grades remained about the same. I just had to live with the stifling anxiety over getting in trouble for not getting my homework done.
Thankfully by the time my kids came along schools started pulling back on the volumes of unnecessary homework. I also never pressured them to get every assignment done, but instead asked them if they understood what they were doing. As adults having completed further educational programs, they did just fine. I'm glad that as time goes on, kids are getting more of a chance to be kids.
My son made a mistake on his state taxes and his return was rejected. The letter he got back basically said "we couldn't verify your reported property taxes, so you can resubmit a correction or do nothing and accept our version of your taxes" (where he gets back about $200 less because of a typo.)
So, like, yeah. They're just comparing your notes to theirs, with the default benefiting the state.