Other people have pointed out in this thread that the language of the acceptable use policy is so broad that it arguably violates it to sell a Basic Instinct DVD over the Internet. Given this, PayPal obviously won't actually be pursuing every violation, but rather wants to create as many violators as possible, giving them unlimited power to close the accounts and claim damages against nearly everyone.

The people it actually takes this steps against will be those who violate some secret internal policy, presumably. They don't enforce it against every violator because the number of violators means it would destroy their business.