It's been a long time since I've looked into this, but things like this generally are regulated (in the US). The sweepstakes promoter generally must post the odds of winning, and can't actually require a purchase of a product to enter (though you might need to pay return postage and wait 2-4 weeks for the free entry option). Some states have stricter requirements and you'll often see nationally advertised sweepstakes specify that they're not offered to residents of those states.
It was regulated in the sense that it gave the odds of winning, just as how lootboxes/gacha mobile games just now are giving drawing odds (since there is starting to be a crackdown on those).