I have not worked in America, but I have worked with Americans so this is hard for me to confirm, but I simply think that weaker work-related laws simply lead to people having on average more fear of losing job and thus there's more internal/social pressure.
Anyway I did travel America though and lived 7 months in Ohio (went to OSU for exchange) and I don't know in which fields do you think where expectations are higher.
Food industry, including fast food in US, has extremely low quality/pressure and expectations. It didn't seem to me like people work harder in that field.
Building/craftsmen too I didn't see any noticeable difference at all, as most of these people are generally self-employed or in very small business anywhere in the world.
People working in shops or supermarkets, again, I haven't seen any noticeable difference.
Thus, I ask, what are those field where expectations are "generally higher"? Dystopic corporate ladder climbing?
Also, I have few colleagues that worked for Facebook, Indeed and Google (specifically Youtube) in Dublin and they recounted that it was American coworkers being consistently late, lazy, and taking every single excuse for class actions and work avoidance (such as getting PTSD or problems over any minor issue).
Also, Europe is a very huge place with different cultures.