Interesting trend in retailing customer interaction

This has nothing to do with knowledge management.. I think.

Something I've been noticing of late (which doesn't mean it has not been happening for a while) is the following interaction at a retail store:

You go up to, let's say a coffee counter. You order a coffee, are given the product, and informed of the amount due. Let's say the amount due is $3.57. So you had over a $5 or a $10 bill. The person behind the counter gives you your change, to which you respond "thank you," and you receive a pleasant "you're welcome" in return.

It strikes me that in this exchange, as a customer, you are never thanked for your business, but, instead, thank the clerk for giving you back what is yours in the first place.

Isn't this a bit backwards?

It makes even more precious those few situations where staff at retailers go out of their way to thank you for buying from them, or even coming into the store. Fortunate I do run into these occasionally, and it sure encourages the next visit.