You’re kidding me, right? How hard did you actually look? You can find loads of $500 or less apartments (real ones, not like the shoebox you linked) in the US, and you don’t have to live in the middle of nowhere. Here’s a bunch in Raleigh, NC, which is part of a major tech hub (Research Triangle Park):
https://www.apartments.com/raleigh-nc/under-500/
The US doesn’t have a housing affordability problem, we have a problem with everyone and their brother, regardless of income level, thinking they should be able to live in heavily populated, high cost of living cities.
The US also has a problem with home-owner NIMBYs imposing their ideas with the force of law on what kind of housing should be allowable on other people's property.
In America, we don't even have the option to live in that sort of apartment, we instead can only 1) rent a room in someone else's house (and be at the mercy of their awful idiosyncracies and have negligible amounts of privacy) or 2) not have a place to live at all.
Not nearly as expensive than popular cities in the US.
To be more precise, many non-US popular cities have a lot more supply of rental units at low cost than most US popular cities. The cheapest apartment available to let immediately in many non-US cities is far cheaper than the cheapest apartment available to let immediately in, say, Los Angeles area or SF.
For instance, there's apartments you can let in Tokyo for $500 (or even less!) (https://resources.realestate.co.jp/rent/what-can-you-rent-fo...) but there's literally no equivalent in the US. Like at all (if you find a counterexample please let me know!).
That is why allowing dense and tall development (free of NIMBY interference) matters.