And what about all the almost-kills or partial kills? Would anyone really feel comfortable saying good morning to someone whose legs they cut off, or who barely escaped their Purge Night machine gun rampage? And shit, we're only talking about murder part -- what happens to all the sex offenders the day after? "Look, Graham, we know that by Purge law, the things you did yesterday were legal. But I'm afraid the children aren't OK learning math from a man who kept them in cages while he put on lipstick and- well anyway, Graham, you're fired."
Actually, are you even allowed to fire people for things they did during the Purge? If not, is there a legal organization to fight wrongful Purge-related terminations? Is it assumed that every boss would be dead after the first Purge and the question would never get raised?
Now that we think about it, anyone worried about wrongful termination could simply wait 364 days and fire problematic employees on Purge Night. But wait, what does that mean for protected groups? Could a racist boss fire all the minorities during the Purge? Could they rewrite the company's HR policies to allow groping? Wait, could they take all the pensions and burn the place down? Also, the real estate market would go nuts -- you sure as hell wouldn't want to keep living next to the neighbors who tried to burn you alive. Also, wouldn't your life insurance policy have about a million complicated clauses concerning where the money goes in case your wife purges you? It just goes on and on.
If you really wanted to make an interesting Purge film, start the movie with motorcycle murderers loading up their guns, immediately cut to "12 hours later ..." and show those motorcycle murderers groggily going back to work at the mall where all the neighborhood buys corn dogs from them -- the kids everyone saw kill their families. That's a movie.