I've heard that the cameras are only there a couple of days a month. If the production crew knows something important's going on they'll plan on being there, or they'll set up special days for the family so they can film it. They're there all day on those days but they're not there every day of the week which is why most of the episodes are themed around special days or they're clip shows of random footage thrown together.
Regardless of how anyone feels about Jon and Kate, I think it's insane to go as far as saying the filming is abusive to the children. People throw "abuse" around so easily these days; of course it's extremely important to alert someone if actual abuse is detected or witnessed, but filming the kids at theme parks, doing pottery or all watching a movie is hardly abuse. The kids are all absolutely adorable, loving and caring... you can see how they love to help out Jon and Kate and they all take care of each other. Even the bratty tantrums and comments make them seem normal, at least in my book. Jon and Kate's form of punishment is sitting in the corner until they calm down or apologize - they've never been hit or verbally abused. Was not letting the boys have cupcakes on their birthday extreme? Absolutely. Is having the cameras around annoying? I'm guessing it could be. But none of this is "abuse." With so many kids out there actually being physically and mentally abused and needing help, I just think that's a mighty big word to so casually throw out there regarding cute kids on a TV show whose parents obviously love them, despite their supposed flaws.