as far as how police would know, when they issue a ticket, they enter the license plate on the MDC and attatch a note to the registration saying "unpaid fine". then the registered owner would go to LSPD HQ to pay the ticket, and the officer would remove the note. if the person has too many unpaid fines, then there'd be a license suspension issued until they are caught up. if after 15 days the fine is still not paid, an arrest warrant would be issued. thats how it would happen IRL