I doubt you have accurate statistics that no one in the US has had a ban botting, Honorbuddy or not. Ones that don't post on the forums, ones who may not even be using the account at the moment. A ban wave insists the idea blizzard has solid proof of how to detect the bot. Very technical, and that wouldn't mean they would herd all of them up and ban them, that's a straight loss of money across the board. They probably ban the first early stragglers that they looked at personally, then once they figure it out for sure, they just ban the whole group by detection. Honorbuddy's tripwire will trip if anything suspicious were going down with the warden, however incase they somehow got around it, a banwave is possible.
You can't "predict" one.