Like someone pointed out on ABG,
there's more than one stop on the city test, so I'm thinking the shut-off interval is so long that the only portion they can take advantage of is in the first part of the hot-start phase. The only way the cost can be $500 is if they're charging extra to install the system at the dealer, since only the most expensive stop/start systems w/ regen braking, probably for mild hybrids, are
that expensive. So, yeah, if they can't get credit for it, then consumers be damned, they won't bother.