Getting back to my original question: I often get better service from grocery store workers (depending on the chain, of course), than I do from restaurant workers. Yet no one pays them a tip. Same goes for Costco employees. Often the worker at the REI store will spend an inordinate amount of time helping me. No one pays them a tip, and they don't get a commission. From my perspective, all of these people are actually providing a service to me that I actually want, when I want it. Whereas with waiters, they are typically forced upon me. It's usually the exception that I want some service that requires a waiter.
The point being: There are more ways than tips to build a culture of good service, and it's inane to think tips are needed to maintain quality.
Actually, in stores like Nordstrom, you get a lot more service (if you want it) than at a restaurant - even when you don't want it. I avoided them for years for this reason. They have a fair number of people who spend much much more time providing these services than doing the other stuff you mentioned.