Its not a whole computer, its a tiny fraction of a whole computer. And that whole computer is in a giant datacenter hundreds of feet from massive ISP interconnections and only a few hops of hardware away from it. Meanwhile the residential customer is probably many miles from the nearest interchange, often even hundreds or more miles.

Location, location, location.

I do agree the over the cap costs imposed by residential ISPs are many, many multiples of their true cost, but they're mostly there to discourage use not be a reasonable price. If you want business level usage hop on their business networking where pricing models are more designed for more average load.