The depreciation is a result of the value to the buyer, though. They’re a PITA to maintain because everything on them is an odd size and made from the worst possible material.
Unlike a permanent home which has mature ecosystems for completely refurbishing them, a better bet with a mobile home is to use it up and throw it away.
> everything on them is an odd size and made from the worst possible material
I've found that outside of light switches, electrical outlets, and bath tubs, much of the stuff is the same or similar (2x3 instead of 2x4 or 2x6 walls for example, or 1/4 foam instead of plywood sheathing) than regular houses, and can be purchased from Lowe's or Home Depot at regular prices instead of super high prices from the only mobile home parts store around here.
Unlike a permanent home which has mature ecosystems for completely refurbishing them, a better bet with a mobile home is to use it up and throw it away.