Activation of customer data-less internet access. Automated routines by signed/marked (SIM-card/MAC-address similarity) gadgets that are activated on first use by payment-details. Typically, first period (month?) is bought on exactly first connection to the internet. This can be in the fashion of Buypass or other, by buying a modem/router with an identifier-number, marked as noted above. If the payment happens on a up-front basis, you will never have payment problems from the customers and customers who are not... can choose to go elsewhere!
The up-front/pre-paid solutions can be handled also as the customer buy the device and from there on needs to visit a website to renew the subscription!
This idea makes it apparent that no customer data ever needs to be handled and that IP's that take part in illegal stuff can still be traced by Police authorities by the usual mechanisms... Good?