Mobile wireless stuff (EDGE/3G) is going to great lengths to avoid dropping packets, so if you get conditions right (moving train in the areas with poor coverage is one place where you can easily see this), you can get the packets "reliably delivered" in 20 seconds and more.
TCP has been designed in such a way that it interprets packet drops as a sign of "congestion" (which was typically true in ye olden days of purely wired networking), and it will start sending less data in response.
Whereas in wireless networking, occasional packet drops are just a fact of life and are not indicative of competing flows trying to share the channel. So it actually makes [some] sense that wireless protocols try to compensate for the behaviour of the transport protocol used by 90% of all data: TCP.