When I pay people to perform services for me, I don't operate under the illusion that we've become friends. I go to my favorite restaurant in Chicago and get brought a couple dishes on the house as soon as we're seated --- that's not because we're friends, it's because I've built a business relationship with the restaurant (and its servers). It's exactly the same dynamic as exists for airline customers who pay up for the airline lounge.
That relationship with the servers, by the way, also has a name: it's a principal-agent problem. Servers have competing incentives: to serve the interests of customers (better service) or the business (reduce ongoing costs). Tipping shifts the incentives around. You could attempt that shift with other mechanisms, like after-dinner surveys, but you know how well that'd work.
It costs time, effort, and money to provide better service, so I'm not from where you get the moral dimension of having to buy them. They have a cost; of course you have to buy them.
