Harry .......
Great point re margin. Walmart and other discounters work on the same principle. If I was a casino operator, I would rather make a little on a large volume than make a higher margin on far fewer players. Some VP players (me at least) get bored after playing VP for more than 3-4 hours straight and migrate over to other slot machines and table games with higher hold margins. Re accuracy of play, I doubt that more than a small percentage of even knowledgeable player more than about 99.8% accurate over an extended time period. Considering this, I think casinos make some money on positive game situations of less than 101%
http://www.lasvegas advisor.com/ qod.cfm
.... for one additional point.... The reality is at the opposite end of the spectrum.
A casino only has incentive to offer machines with strong payouts when
there's a meaningful body of players who seek them out and will play
elsewhere if another casino inventories them but this casino doesn't.
If players are indifferent, all paytables will be mediocre.
The ideal is, of course, if these players don't play with perfect
skill (and few do). They give the casino a machine hold that may be
thinner than offered by players on other machines, but can be
compensated with greater play volume.
Give a consumer/player a better deal and, where there's an appetite
for it, they'll "consume" more ... getting greater satisfaction out of
the ride. Usually/hopefully it turns out to not be a case of, "We
lose a little on every sale, but we make up for it on volume!" 
The paytables may carry reduced player benefits, but more often than
not they're present only because of the word having been spread.
- H.