The problem is voter intimidation-- I don't have any warrants either, but these signs were posted on my campus by a conservative-leaning group to scare away people from voting. The logic being that minorities (who are overwhelmingly left-leaning) are criminals, so telling criminals they shouldn't vote will help republicans win.
Pennsylvania just reached a record in eligible voters, and the conservatives are running scared because they know that the more people who vote, the less likely they are to win, because the traditionally disenfranchised voters are majorly left-leaning.
The Republican idea that they need to prevent voting so they can win, and redistrict so that the votes of urban populations don't count as much and they have to wait in long lines (see: Ken Blackwell) is a serious, reprehensible problem. This is not something to joke about. There are few things as un-Democratic (and I mean democracy, not the party) as trying to prevent fellow citizens from voting.
Do I think it would be wrong if police caught a serial killer coming out of a polling place? No. I do think that threatening people with unpaid parking tickets with arrest upon voting is ridiculous. And obviously not something the Philadelphia Police would do. They've lost 5 officers on duty in the past year-- they have much more serious issues at hand than parking tickets or minor misdemeanors.
The flyer itself could be dismissed as a stupid prank, except it reveals something considerably more dangerous-- that people in this country think that it's okay to lie, cheat, and steal to keep the 'wrong' people from voting. EVERYONE should vote. I would be unhappy with a president or any other candidate if I thought they had won by anything but a fair election. The past few campaigns have shown me that a few of my fellow citizens do not feel this way, and experience has shown them to be overwhelmingly Conservatives.