AWS architects its network to push traffic away from it as soon as possible. A possible explanation for this behaviour is the high likelihood that the AWS backbone is the same as that used for amazon.com
Probably true. Alternative explanation is that 'hot potato' routing has been the standard BGP traffic management policy pretty much since BGP peered out of a cloud. Problem is hot potato (aka closest exit) may mean dumping traffic at a congested local port. For a transit service provider who wants to sell on quality, that traffic policy may not be the best idea. Especially not with the big 3's capacity buying power vs other ISPs or telcos.
Asia's also always been an interesting traffic engineering challenge. For a long time peering was via JPIX or HKIX which leads to Indian, Singapore or other large parts of Asia taking a long route via peering. Efforts to grow that in places like Mumbai or Singapore are growing, but customers need to look closely at how their ISP(s) peer with the clouds in any region.