It makes us uncomfortable to be pampered or if the serving staff are overly friendly or chirpy - it feels insincere to a Brit and puts us into a defensive mode.
If serving staff are polite (or at least not surly) and we get served in a reasonable amount of time then that's all we ask for and we'll tip 10% if there was nothing wrong with the meal, or put some change in a tip jar if we only ordered drinks.
Traveling to the US as a Brit is an affront when you first experience "service culture". You become desensitised to it after a while (and can even have some fun with it) but initially it's a genuinely uncomfortable experience and it blows my mind how different "normal" can be across English-speaking cultures who share a hell of a lot of history and culture.
Is that really true, though? The US is such a mix of cultures at this point (and even the more dominant cultures have diverged so much), that I'm not sure it's accurate to say that Brits and Americans generally share all that much culture. History is there, yes, but it's been over 200 years, and history fades.
most people working in the service industry are not teenagers and college kids. For restaurants and fast food joints adult workers are more common.
https://datausa.io/profile/soc/fast-food-and-counter-workers
https://www.epi.org/publication/wage-workers-older-88-percen...
The average retail worker is over 40.
These aren't "summer jobs" for pocket money or children's first steps into the workforce, they're the jobs adults depend on to keep their rent/utilities paid and their families fed.
Someone 25 years of age and older can deliver exceptional service, they just aren't paid enough to care to.