[jerf]

"They can just throttle access to Google documents to something like 4 GB per hour"

No, that's not likely to work. I'm sure there's far more legitimate users using 4GB of documents per hour than abusers right now. You have to remember things like bulk downloading, bulk scanning, bulk backing-up, shared automated accounts doing all sorts of legit things, etc. are all legitimate use cases. You can't just throw out all "big uses" or your enterprise customers are going to pitch a fit, and that's a bigger problem than people abusing your storage for a while.

(Those things will still have different access patterns than abusers, but thinking about how that will manifest and could be detected is an good exercise for the reader.)

[Someone]

I would guess those enterprise users pay for Google docs, and could be exempted from throttling on that basis.

If they don’t, Google wouldn’t lose much by throttling them, would they?