Estoy terminando de escribir el Data Links de esta semana (suscríbanse, que es gratis) y mientras terminaba la recopilación de enlaces que voy dejando desperdigado por mis notas he encontrado esta joya: Payment Processors Are Profiling Heavy Metal Fans as Terrorists. No solamente lista lo obvio (parece ser que es muy difícil usar Paypal para comprar una camiseta de una banda de rock de nombre Isis), sino que además previene sobre todo tipo de inconvenientes en ese futuro que se atisba en lontananza en el que los pagos en efectivo son poco menos que imposibles.
For example, if you're a smoker, and you try to buy tobacco products from a U.S. online seller using a credit card, you'll probably find that you can't. It's not illegal to do so, but thanks to a "voluntary" agreement with law enforcement authorities dating back to 2005, payment processors have effectively banned the practice—without any law or court judgment.
Another example that we've previously written about are the payment processors' arbitrary rules blocking sites that discuss sexual fetishes, even though that speech is constitutionally protected. The congruence between the payment intermediaries' terms of service on the issue suggests a degree of coordination between them, but their lack of transparency makes it impossible to be sure who was behind the ban and what channels they used to achieve it.
A third example is the ban on pharmaceutical sales. You can still buy pharmaceuticals online using a credit card, but these tend to be from unregulated, rogue pharmacies that lie to the credit card processors about the purpose for which their merchant account will be used. For the safer, regulated pharmacies that require a prescription for the drugs they sell online, such as members of the Canadian International Pharmacy Association (CIPA), the credit card processors enforce a blanket ban.