A good judge would have ruled the sign inappropriate, and it wouldn't apply to ANYBODY, rather than just letting off the good middle-class people.

Because it shouldn't matter the slightest bit whether someone had previously gotten tickets or not. Either the sign, and the rule, is appropriate for everyone, or it isn't appropriate for anyone. But it is NOT a sign saying "free left turns for the ticket-free and appropriately subservient".

Would you be as happy if it were a young black man with twenty tickets already for driving while black who was let off by the judge and not your wife?

This judge obviously saw a woman who had made a mistake rather than one who had set out to break the law. And how do you know how many black men, or women for that matter, this judge has 'let off' or not? You're just assuming things based on your own prejudices.

a judge - otherwise, a computer could handle the whole case. Write the ticket, demand the fine.

And no, I'm not basing my views on prejudice, but on statistics.

Judges have discretionary powers, and use them all the time. Badly, in most cases. Yes, most cases.

As I pointed out earlier, the judge's discretionary power COULD have been used to replace the entrapment sign with something more legitimate. And I don't know how many blacks THIS judge has let off, but I don't know how many judges can fly either. I just know the odds aren't very good, and that you can't decide from a single anecdote, especially if that anecdote happened to oneself.

Basically the OP says "I got off, and therefore this is a good judge." And I don't buy that logic. I suspect the judge is closer to the average than to a judge that makes this sort of ruling independent of social class. We COULD look up the judge's record, but that's not the point - the point is that the judge's record, and not a single anecdote, is needed to make meaningful statements about whether a judge is "good" or not.

I wouldn't have brought up race, as it's not relevant at all - except that the largest, easiest-to-identify group that gets consistent, measurable unfair treatment from police is identified by race in our culture. It's the example I chose - the same argument if you contrast the treatment of protesters breaking the law regarding public access to things, and construction companies, especially large ones, breaking the same laws. One side sees wonderful justice, all the time. The judges make common-sense exceptions for them on a daily basis.