well... most buffets I've been to have a reduced price for children since they are typically going to eat less. But it is hard to make good analogies between physical/virtual things.
True those analogies are very hard to make, as evidenced by the media piracy debate and "you wouldn't download a car, would you?"
I think the majority of my vitriol comes because it's an asinine way to split up service based on what we're assuming is bandwidth concerns. If they want a tiered service, then put in a tiered rate structure. The "laptop" rate gets you 300kbps, the "mobile" gets you 100kbps. Simple.