I can sympathize with your frustration, but here are a couple of things to consider:
1. According to the FAQ on totalwar.com, you don't have to active a retail copy on Steam in order to play the single player. You only need to active for multiplayer. So if people did get their preordered copies early, they could play before the release date.
2.Amazon is often slow in filling preorders. It's a really a problem with pre-orders in general, and not just them, but they seem to have a lot of trouble being timely. So, if having it on day 1 is a priority, I would just look for it at a brick and mortar or get it on Steam and not bother with a pre-order at all.