Numbeo is a site that offers comparisons between cost of living in various cities.
It tells me that rent for a 1 bedroom in Johannesburg is around $440 USD per month. In Denver, a mid level American city, you would be paying $1790 usd.
Also keep in mind that if you want health insurance in the US, you might end up spending $5k-$10k for just the insurance, getting care for anything beyond a yearly checkup is going to cost more.
In SA we also have to use private health insurance as the state run facilities are really bad. We have no safe public transport and those who can afford their own car usually have one. Our policing is sub par and many have to pay for private security.
We also have a very high income tax rate. Up to something like 45% depending on your level of income.
If I for instance saved 10% of my salary vs someone earning comparatively the same in the US, I would have far less buying power in the world in general.
Overseas holidays are something very few can afford. Spending ZAR overseas is rough.
No doubt there’s a reason that so many SA choose to work overseas. My point was more that $15usd an hour just doesn’t go that far in the states, even though it sounds like a very livable wage outside of the US.
Even within the states there are massive discrepancies. $15/hr in San Francisco probably means you are on the edge of homelessness. Meanwhile that same pay in the southeast might be enough for a modest life.
https://income-inequality.info/
Earning $30k in the US puts one in the top 5% of the world's population with respect to income (adjusted for PPP).
https://howrichami.givingwhatwecan.org/how-rich-am-i