Do you have quantifiable evidence, or is your statement speculative?
Even our cheap dishwashers here will perform well without pre rinsing, and I find it difficult to believe that American dishwashers can’t do this.
Based on what I've seen in person, heard in person, and all the internet talk of poor cleaning and stinky filters over the last 20 years.
I literally had a friend who went tall tub and the spray arm holes started clogging. People at Sears in the early 2010s complaining how their new tall tubs couldn't clean.
YouTube videos of people cleaning gunky filters.
The only reason you hear less about it is because people just alter their loading habits (pre-rinse) until the problems are no longer noticeable. Which for many isn't that big a change because they've always been pre-rinsing due to the fact so many older dishwashers lacked good water filtration.