Back in my day you just did what the teacher told you and didn't question it. The problem is and I'm not accusing you of this is the parent always seems to take the kid's side..... Suffering through the busy work doesn't last forever.
Oh, but it does. The busy work just gets ... busier. Like having to turn in an outline for a 40-pg research paper, when you're a person who doesn't outline. Doing the outline after the paper, just to have something to turn in, is busy work.
I come at these things from a different perspective, though, as my parents had no qualms about telling a teacher she (or he) was wrong, and proving it. They had no patience for idiocy in the schools. We used to have this form every year for some government thing involving kids on the nearby reservations, and my mother would write "None of your business" or "None of your d..n business" on it and send it back, un-filled-out. When a homework assignment was to watch the movie Sybil and do a report, my mother told the teacher he was going to have to find something else for me to do because we didn't have a TV. He said I could go to someone else's house. She told him just how ridiculous that was and that I was not going door to door asking to interrupt someone else's TV watching for a homework project. My mother would definitely have told someone where to stick all this "math mountain", "hundreds chart", "show your work" stuff. I'm getting to that point myself, having mercifully skipped most of it with DS and now only just getting rolling with DD.
On the other hand, about taking the kid's side, if my teacher sent home a report that I was messing around or something in class, my mother had no qualms about sticking that to me, either. My elementary school was mostly farm kids whose parents took education very seriously, and if you got in trouble at school, there would be worse trouble at home. But if school was the trouble, that was dealt with, too. That school is still number one in the district, with the next generation of the same families.