I’m with you on this, totally. I am a 100% “thank you” person and maybe a 30% “please” person, which is probably higher now than, say, a decade ago. My version of please has long been to turn up the request phrase significantly at the ends as you do a question.
I get that clerks have thankless jobs—most people have thankless jobs—but that said, I will not thank the store for taking my money, and in the moment, the clerk is the store. If the store does say “have a good one”, I generally reply, “you too”.