One thing worth noting about the difference between 'how laptops use internet' and 'how phones use internet' is that computers will open up TCP connections like they're going out of style, whereas mobile devices are generally optimized to avoid that. The switching gear on the carrier side assumes the latter, not the former. It may not necessarily tax spectrum, but it will tax the networking gear, especially if you're torrenting.
OK, it's been a couple of years since I built 3G SGSN/GGNS "routers" for mobile internet, but that's not how the system worked back then at least. The network didn't know, or care about individual TCP connections from the subscriber. In fact, the network didn't really care about the mobile data at all. All the data to and from the mobile was/is heavily tunneled. The only parameter of the user traffic the network ever even looked at was the IP address. And even that was very limited. The destination address was checked for incoming traffic to the mobile to decide which tunnel to put it in. The source address of the mobile's packet was checked on egress from the network, if egress filtering (to prevent the mobiles from doing IP spoofing) was enabled.
This was by cultural design, i.e. given the option telecoms people will bury their problems under yet another layer of the communications stack. But, by happy accident, it's what preserved the security of the provider networks, more or less. We haven't had any major, large scale outages due to e.g. mobile worms etc, as it's very difficult to affect what the network is doing by sending IP-traffic over it. The network basically doesn't listen to the traffic in the tunnel and hence can't be affected by it.
Now, the ugly thing on the horizon when I left was deep packet inspection, and indeed if you do deep packet inspection then you can run out of resources to do TCP connection tracking. However, the network isn't really dependent on this to "work" (well shaping is a possible exception). So the answer to that question then, to the providers that complain is "Cry me a river. If it hurts when you do that. Don't do that then!"
P.S. If they changed all this in 4G, i.e. making the network more sensitive to what the mobile actually does on the network level, then, I'm of course all ears.