* My parents didn't become very involved in either my homework or my school life. Other than helping me make a papier-mache pumpkin when I had the role of "Great Pumpkin" In our 3rd grade school play. I feel like I'm much more involved in my children's school and homework, but don't know if that's due to school specifically, 21st century parenting styles, personality (mine or my parents) or most likely, because I have children who have learning challenges.
You missed the reason that I think is most likely in my case, and possibly yours as well - I didn't really have much homework until 7th grade, and even then, it was probably less than my daughter had in 3rd. The occasional project that my mother nagged me about, but not more than two or so of those a year. I know you said your 3rd grade teacher sent home homework, but also that all the adults were shocked by it. My parents rarely got involved in my school life, but that was mostly because I kept school stuff at school and home stuff at home. Things are much more "mixed" for my kids.