I think it's an excellent idea.
The whole point of a fine, is that it dents your wallet.
If you've got a bit of money, then £60 doesn't dent your wallet in the slightest. If you're very poor, it's a large amount of money !
Parking tickets are a prime example. Rich folk in London park where they like, and simply pay the fine. If it was means-tested (so their fines were £10,000 or whatever) then there would be a *LOT* less illegal parking !