Re: And this ladies and gentlemen...
Correction - it's possible to know which are letters and which are numbers. Not everyone does, and why should they be expected to?
I've seen plenty of UK number plates like OOO7 ABC - the first two are O's, the third is a zero. I know this because I happen to understand the format, but it would be unreasonable to expect everyone to do so, and to base parking enforcement fines on this, particularly when the UK number plate font has identical characters for O and zero, and for I and one.