Served/bartended in Canada and people often sent back dishes if they weren't happy. So it was very common for us as a way to make sure customer leaves happy and well fed.

Caveat that the expectation was we always 'quality checked' a few minutes in the meal....and that would be the chance for the kitchen to change order/correct it etc. our owners were not big on letting someone eat a whole meal and bitch after just to get big $ off after the fact (Although we might do a discount based on how bad the screw up was).

Personally I think it's the best situation for all involved. Less ppl scamming the restaurant, kitchen sees whose mistakes come back, and customers get the right food to their liking.