Earlier quoted context omitted.
While an EU citizen can at least roam in the EU fine, and a US citizen can roam the 50 states, seems that roaming outside of that would be exceedingly difficult and expensive to get appropiate visa (if they exist)
The "quiet part" you don't say out loud is you don't get work visas - you pretend you're a tourist and survive on those. However, an American could spend years just traveling the United States, and that doesn't even cover the possibility of the territories, etc.
Yup. I actually imagine a Californian could probably spend a LIFETIME roaming California and still not see everything that's worth seeing. The late Huell Howser did just that, but he only scratched the surface of the amazing places to visit in CA.