> Now they're run based on the data, and the data says they have enough loyal-to-a-fault customers like the author that chronically understaffing is more profitable than providing a good experience.

If they are indeed saying understaffing doesn't matter because their current customers don't care, their loyalty numbers will only go up because of that sampling bias. Relatively upscale fast casual places (e.g. Chipotle) will replace McDonalds for the customers they lose. The circle of service industry life.