In my experience as a hobby sweepster, it just isn't true. None of them makes that claim. Each cover letter states that the sweeps can be entered without ordering, renewing or making a contribution. I might have to search for the instructions. These rules state how to enter without ordering, when the entry must be postmarked or received, and when the drawing will take place.
People are upset that they've been manipulated.
But manipulation of consumers is nothing new. If you watch television, listen to the radio or read magazines, you're subjected to manipulative tactics of one kind or another. The sponsors of sweepstakes are in the advertising business. It's their job to get our money. It's our job to be smart, to read the fine print, to prevent ourselves from being deceived.