Perhaps Texas is a bit different than Michigan. Customer owned cylinders are not in the least bit rare here. I own about a dozen of this size, and my welding supplier doesn't give two shits who owned it before me. They'll swap it. They make their money on the gas, not the cylinder. Its in their best interest to have customers bring them cylinders.
Michigan is still part of the US. The DOT and the ICC used to swing a $10k hammer in the old days on people who filled cylinders without the permission of the "owner". The "owner" was the company who bought 100 or 1000 from Chesterfield, Coyne, Worthington, etc. and had his company name stamped in the shoulder.
I am retired and don't care but "ARCO" was a company based on the east coast (I think). ( I think they were part of the old National Cylinder Gas or maybe Tri Power group? Too long ago to remember for me.) Air Gas and Praxair and the rest have really screwed the ownership bit up. If they're no longer in business, somebody owns that tank. It isn't the guy who carried it home from work, ground the neck ring smooth, and said " it's mine now".
I have very little sympathy for a company that couldn't keep track of their rental property. I thought the "loss of use " laws were a tiny bit unfair to companies with the misfortune to hire a few thieves. But, at the same time, it ***** for a WS to spend $100k over and over on cylinders just to collect $5 or $10 month and have a competitor get the benefit of gas sales without that investment.
And, yes, I have taken photos on competitors docks and trucks and sent "cease and desist" letters. It is about as much fun as repo work or holding shoplifters for the cops.
I am regretting my inability to avoid this topic already. I am not in the biz and Michigan is way outside my old territory. I wish I had just made fun of your welds.