I've tipped cable installers (and I'm not a bluecollar worker) - I assume that anybody in service industry in principle can be tipped for providing excellent se

I've tipped cable installers (and I'm not a bluecollar worker) - I assume that anybody in service industry in principle can be tipped for providing excellent service. Painters, movers, furnace people, superintendant, anybody who can provide crappy, basic, or excellent service -- I want to support, reward and encourage excellent service. I cannot tip the phone customer service reps, but if I get a really helpful one, I'll ask to speak to their supervisor and put a good word - for what little it may do. In my mind, it's partly about showing gratitude, partially about encouraging behaviour we want to see (understanding that in terms of natural selection, I can tilt the outcome very little compared to the priorities and prerogatives of the company and management, who are typically at odds with me as a customer)