I've had relationships with Ski Shops that have comp'ed little things or hurried (ignored a few day turn around to get my suff done in an hour), but that's shops that I've known and done business for years, as well as shops that know I teach (the whole, comp now receive referals later philosophy).
At my Ski School, we've done similar programs on busier days, when we get a ton of 1st timers out and waiting for lessons, we'll provide a few instructors to give them some basics while they wait. Comp'ing them lessons on what their different peices of equiptment are, how to put them on/take them off, walk around, begin sliding, how to stop, how to get up from a fall, and how to side-step/herringbone up the hill, etc. By doing this, not only are we helping them and keeping them busy, but we are also able to break some students into higher levels right off the bat (keeping students to instructor ratio's lower).
But aside from skiing, I've typically only run into comps when spending a decent amount of money. However, there have also been times, particularly with mechanics, when a secondary problem was found and fixed and I was only charged for the initial problem.
Overall, I think many people who works in "services" tend to see customer happiness as greater potential for earning, "if they're happy, they'll come back, if they're really happy, they'll bring their friends".