What you’re describing may be an issue. I suspect it is a tiny minority of the speeding tickets written. The above poster is advocating for well advertised limits and automated ticketing. I think this is a very reasonable solution to an undeniable problem: driving is dangerous, speeding more so.
The situation your describing a contrived edge case and is not a valuable contribution to the discussion at this stage.
“Just don’t speed” is, by and large, a very reasonable thing to ask of drivers.