Prag, with all the distractions in the classroom I doubt kids can finish all their assignments in class. I've also seen the work that is expected. Not very challenging to say the least. If my kids don't get homework from school we give them work out of the same workbooks they use at school.
Trust me, my kids have more than enough playtime with schoolmates and organized sports and video games and we have sit-down dinners.
It's all the way it is approached. Kids have to learn how to learn or they are mearly memorizing and that won't help solve problems.
I teach my boys "there are no problems, only solutions," and we have to learn how to apply that.