Theo and comps in poker

At Foxwoods, next to a game's description, there's a letter - L, M, or H - which I'm told represents the level of comps you get for it. I think, L is all fixed- and spread-limit games up to 8/16; M is no-limit and pot-limit up to 2/5, and 10/20 fixed-limit games; H is everything else. I'm pretty sure the way it works is that the L and M games are raked $4[/$1 for most], and the H games are charged by time. Here's the thing, though: I walked by one of these tables at one point, I think the 20/40 stud, and noticed that the charge was $7 per player per half-hour, which for a stud game comes to a not shocking (especially in no-limit) 28 full pots an hour. Plus the fact that, although no-limit is a faster game, and I'm sure 10/20 is as well, does it really make much of a difference, especially in the latter case? Is it just that high rollers expect to be rewarded better, and the house has to oblige regardless of their actual worth?

(I do know that the no-limit players I know are getting more for their level of play... that is a much faster game, though.)