To put it into perspective; at 20 my friend bought a house in the suburbs — 3 bedroom, 2 bath, 0.3 acres; decent neighborhood, driveway for his 2 cars; etc. he’s not college educated and cuts trees down for a living.
Now try doing that in the Bay Area?
It's a bit funny to compare "Europeans" to some place in nowhere midwest and a friend that is almost certainly an outlier.
I'm sure you can find 20 year olds that can do the same somewhere in Europe.
You can look this all up.
While there are homeless and people in trailers, on average it’s because (a) they’re drug addicts who don’t want to live by their own rules (b) people living cheap, trying to get ahead or (c) Elderly, often inept, people who get trapped.
Trailer parks are particularly bad as they lock you into (effectively) renting. Outside of a few major(poorly run & corridor) cities, eg Chicago, SF, LA, NYC, etc the homeless rates are relatively low.
It’s largely that people are interested in particular locations. Not everyone can afford homes in that location, it’s fact of life.
That said, there’s zero need to be homeless in the US. In Detroit you can get a home for free if you promise to repair it.