Simple math is all it takes to understand why this is pervasive. In the classmates.com example, they collected upwards of $75 million in revenue from this scheme, and only had to dish out $2.75 million for the settlement several years later. So for any newcomers, this type of bait is an attractive business proposition; the potential lawsuit years down the line can simply be attributed to cost of revenue. And you'll obviously only get sued if there's money to be won, which means the scheme was a success, so in other words, you want to get sued. The real problem is the judgments/settlements are an order of magnitude lower than they should be.
There's the hidden cost of permanently alienating potential customers, though, which will show up silently in reduced conversion on all subsequent advertising efforts.
