Earlier quoted context omitted.
Why do some jobs in the service industry have tips, and others do not? I've yet to find someone who pays tips for excellent customer service in the big mall stores. I'm sure they exist, but almost no one does it, and this is acceptable. Why?
Generally you have little to no service interaction in these stores. The people in them are order takers, not sellers; whenever they are pushed to sell, the customer finds it intrusive since normally its value-less or negative products (cough, extended warranties). There also never is enough staff. The staff doesn't have time to provide customer service in meaningful ways; they more or less clean, stock, cashier, and…
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.