I've yet to find one of these types of services that you can't access by spoofing the MAC address of a real customer.

A while back, Intel removed MAC address spoofing from some of its wireless cards through a driver update, citing vague "security" concerns. I felt very up in arms about it for a while (why on Earth would you hobble your customer's products so you can make sure they can't violate your moral code!), but eventually decided I couldn't really complain, since the only reason I could think of that I might want such an ability would be to steal internet access.