I don't buy this for a second. I thank everyone for even the most trivial of interactions and I'm certainly not alone (in the US)
Buy a Coke at 7-11 - "thank you!" Take package from UPS guy - "thank you!" Waiter takes order - "thank you!" Support rep puts me on hold to look up issue - "thank you!" Pretty much every retail/store interaction - "thank you!"
I suspect overall impoliteness has seen a bit of an uptick, from my casual observation of the sociomacro (especially during airport and air transportation transit and use), and that gratitude is not expressed in casual interactions as perhaps it previously was.
https://hbr.org/2022/11/frontline-work-when-everyone-is-angr... ("Frontline Work When Everyone Is Angry")
https://psycnet.apa.org/record/2015-28930-001 ("Catching rudeness is like catching a cold: The contagion effects of low-intensity negative behaviors.")
I dug ditches for just one season, and I can still feel it sometimes. The struggle is hard and it real.
My personal principle always is to be polite with everybody. Like that's default mode of operation. No matter what you do with them. You might not buy from them, you might not hire from them, you might even want to keep distance from them. That should have no nothing to do with how you talk with them.
Separate speaking from doing.
It's completely arbitrary really, it's just really noticeable and, well, jarring when you're not used to it/used to different. I'm sure it's similar in reverse (I thanked him and he was so grumpy about it, didn't say a word! (Or he just said 'cheers' back, I didn't buy any alcohol?)).
Maybe he was speaking of management, franchise, and McD corporate?
Or maybe it was a quirk of that store in NYC, or our own experiences are otherwise not representative?
Or maybe he was writing more loosely, about a "thankless", poorly appreciated, poorly compensated, purely transactional job.
When I said "nobody thanked me", I mean the management didn't.
(edited for clarity)