Yes I agree it's petty and illogical - but in that respect it is like the Policeman and besides it makes me feel better. My first and preferred reaction would be to write to the local paper, but there isn't any Dziennik Kutnowskie or similar.
I remember when I got fined for speeding (first and only time) I felt utter indignation at first, was going to write with every excuse I could think of but then I accepted it as fair play.
After all, it was the only time I had got caught and I'm sure like many others in the UK, you end up speeding a bit every day and get away with it.
I've only been to Poland once and never realised you could get fined for jaywalking. No one told me about it at the time. Good job I didn't walk around on my own on Poland's streets :)