I do want to point out that no one is actually complaining about price of just building per say. Trailer is fine and all, but does that 20k cover land and basic utilities like water and heating/cooling (Is it well insulated?) in reasonable price and effort? Is Trailer Park actually located close enough to jobs (I don’t remember gas and time being free) and it is secure from natural disaster?
That aside, NIMBY mindset is generally dumb stance when everyone is taking it. So there’s that.