The kid at the drive-thru might own the place in ten years. That’s not why you should be nice to them.

The practical argument is true and it makes a poor foundation. People in low-status jobs at seventeen do sometimes end up running the place, and being decent as a hedge against that is still a calculation, which is detectable: anybody can feel the difference between respect and an investment. Kindness that depends on a projected return will fail exactly when somebody has nothing to offer. The reason has to be simpler than that.

So notice your own tone at the window, the counter, the call centre. Treat it as practice in being the same person regardless of who you are speaking to. That version needs no justification.