A decent trailer can be a more pleasant living experience than a tiny manhattan studio, I fail to see why that should qualify as homeless. Maybe using an in-between category would be helpful.

There is no in between category. They're classed as homeless because the people doing the classification are of a social class that don't consider trailers acceptable. It's not about material living conditions. It's about social class considerations.

This results in laws making trailer living illegal, converting the residents therein to truely homeless, thereby making the numbers balance again.

Yes, unless you consider a trailer a home but then where do you draw the line? One could go as far as considering a tent as a home but come on, we all know what we mean by home. A trailer is just a trailer.

Consider how people who live in those trailers feel about people like you. If you need an intuition pump consider that most Europeans live in houses that are solid masonry, not plywood and plaster. Your houses are basically tissue paper, trashwood and mud. Hardly a permanent structure.

Your public contempt is reciprocated by the people you do not respect.

I think it's more about the overall situation than just the physical structure. If you have a place you can legally stay indefinitely, and you have access to water/sewer/power, then I think a trailer could absolutely be considered a home.

A trailer is a permanent structure with bedrooms, living room and kitchen, bathroom, which can receive mail. Yes, they’re small. No, they’re probably not anyone’s preferred option. But they’re still homes.

They aren't really that small when compared to apartments in cities. Often much larger actually.