Clearly at the start of the apocalypse when someone was bitten, the virus made them first go to Savage Country and change into their outfit, then depending on what zombie had bitten them, over time they changed appearance to all look the same. Thats the reason why the dozen or so zombies have the same look and outfits. Its just common sense! Can we stop asking for more now. It would break my "immersion" of said reason.
But seriously, I'm just happy the game is still getting great updates because with each alpha, it feels like a new game in a way. TFP have not just thought to put the game gold and start pushing DLC's on us, they continue to work on a game where most of us already own it and they won't make anymore money from us.
Be happy with what we get.