I may be wrong, but I'm pretty sure that the networks don't have the capacity to handle as much as they say they do. Add on to that that someone on a laptop is probably going to eat up more data. Multitasking is easier (I generally only look at one page at a time on my phone, but I might have five tabs loading on my laptop at any given time), and there are more applications available that can chew through a connection (MMOs, torrenting, etc).