Agreed that it can be subjective and can/does happen often. I further agree with you that you are most often to want to pass if someone is doing 40 and the limit is 50+. In those cases, we wouldn't be in the scenario offered in this thread, as you often don't even have to speed to execute that pass.

That said, I underline again that I think a system that impacts throttle at merely 1 over the limit would be a bad idea.