Well, I think it has to do with the fact that the majority of the players is from NA. For example, there are around 14.000 ~ players around for infinity slayer right now, versus around 3.000 ~ in the beginning of the afternoon in Europe (later in the evening the ratio is even worse). So yeah, easily the majority of the games has a US host. The latency difference between two people in NA won't be big enough most likely to notice. However, versus someone in Europe (and in a much worse degree versus people in Australia) the difference is bigger, and certainly noticeable, especially with crappy US hosts.Fair enough, I am in NA so I never notice a significant difference between games so there's no real way for me to tell who is host. I think we can both agree that this is a type of game that needs dedicated servers, but that is just a pipe dream for Halo.
I also have the feeling that there are way more US people than EU people compared to Halo 3, ratio-wise.
Yeah I'd love dedicated servers for this, or at least a search region filter (come on 343).