playing by the rules (in this case unwritten ones)

I'm fairly sure "Stop on red, go on green" is written down all over the place...? :-} To me it's mostly a question of being predictable to other road users; waiting for the lights to change is more predictable than dashing across through traffic. (If there's genuinely nobody else within sight on the road to see you crossing against the lights, then it's a bit of a tree-falling-in-the-woods situation...)

I think I'm now a slightly better person than when I got up this morning.

I can't tell if you're being sarcastic I'm afraid... :-} I just hope I haven't annoyed you too much!