The US requires 5-10 more vaccines for children by 5 years old than Japan does. Japan also has a much more spaced out schedule over those 5 years.
Given that the American health machine is largely driven by pharmaceutical companies, it seems likely that there is some fat that can be trimmed. Did they trim it here? Who knows.
Comparing the U.S. to Japan, or any other system for that matter, with a simple “well the vaccine schedule is different there” is simplistic and almost certainly not useful.
What is useful is to compare the U.S. with and without a certain vaccine or when delaying certain vaccines.
And we know how that plays out because all these vaccines have been added because of specific threats and actual diseases faced by Americans.
I mean kind of? They have a booming tourist industry which seems to negate your hypothesis.