The cleaner tool used to be called Recycler when I was developing it. It used to give players money for every piece of waste cleared like corpses, scrap metal, rubble... even ammo cases.

But after some testing, I noticed a bug and an issue with this.
The bug is doors can be harvested even when they are still working, yielding a lot of "free" money plus the coin from cleaning them when destroyed.
The issue was the amount of money players would get by just cleaning their bunkers. Even a single corpse would yield a lot of coin, since the tool would treat it like a gold chunk. In short, it was too OP.

This is why it only harvest gold and the newly implemented metal, Plasteel. Being able to recycle its own units is ok.

It would make for a nice custom scenario, though. One inspired by the game Viscera Cleanup Detail. It would start as the player only being witness as two factions destroy each other in a randomly generated bunker. The victorious faction then leaves the bunker and then the players gets to play as the janitor in charge of cleaning the whole mess for money, which can be used to buy more janitor drones and tools. :3

I have no idea how to do that since I have never tried to make an scenario, though. xD