If you are USC, you file (and in some cases) pay taxes anyway, regardless of your location. Check IRS website.

You also have to pay taxes in your adoptive country, if you fall in their tax rules (some are as low as 3 months stay)

You follow companies that are fully remote. There’s a lot.

However, most will adjust your salary based on your actual residency. So if you live continuously in Brazil you will earn a Brazilian income, in USD.

That’s something very carrier based.

I also buy my iPhones from the US (way cheaper than Europe), but I buy them at full cost. No carrier lock.

And carrier lock is not apple/ US only, it’s quite popular everywhere on this planet. You buy something in installments? It’s locked. You buy it at a carrier discount w/ subscription? it’s locked. Regardless if it’s SIM or eSIM. I stopped buying phones from carriers like 10 years ago because of this. I prefer to get them cash down.

In Europe carriers can’t lock your phone anymore, unless in contractual period or in installments. But they have to unlock it after this passes.

There are many reasons.

First, infrastructure budget. What was built decades ago when the US was at its peak vs other countries building it now. It’s a cycle, more or less, but you can’t keep it all up and shiny to infinity.

When comes about Airports, US is not much of a transit point for foreign pax compared with any other major airport. US airports were designed only to get you in, fly to you destination and get you out as soon as possible. They’re the ugliest airports on this planet. Changi, Doha, Dubai, Munich, Frankfurt, London, Kuala Lumpur and so on are designed to get you into the airport from somewhere else, make you wait in transit and then fly you out.

Different mindset: where infrastructure is not an issue, cost efficiency is. This is something Japan has too, hence the outdated infrastructure in some systems (banking, local trains). If it works, no need for upgrades. This is where commercial buildings comes in. In Japan, the local trains are very efficient and very old and stations focus more on functionality than on being pretty. NYC subway was like this too until some time, but now it’s ugly, dark, old and efficiency is rock bottom lol. Still the best in the US, but very far away from any other major transit system in Europe or Asia.

Also, keep in mind that the commercial sector in the US is suffering and thus reducing physical presence (either some places disappearing entirely, or some places are removing stuff). For example, in Manhattan at my local 7-11, they don’t sell food/ sandwiches anymore from the shelve, you need to ask for it. That’s because of theft.