Interesting that you mention UDP, because I'm in the process of adding hard-limits to my service that handles UDP. It's not trivial, but it is possible and while I'm unsympathetic to folks casting shade on AWS for not having it, I decided a while back it was worth adding to my service. My market is experimenters and early stage projects though, which is different than AWS (most revenue from huge users) so I can see why they are more on the "buyer beware" side.