I'm a Londoner and I don't see why things should be draconian if someone makes an error. Just send them a bill for the normal charge if they go in without paying once. Maybe for repeat offenders charge 10x.

Which part? Congestion charges or Byzantine rules designed to obfuscate? If the former, so do I. If the latter, why not simply charge the fees you want to charge rather than be shifty about it?