You are right except last I knew it was costly compared to other forms.
Oxygen hacker had a good write up on it. all the O2 was the same in reality 99.99% pure or better. industrial was put in tanks and sent out. med required vac of bottles prior to refilling and had to be 80% or better. and air grade has to be dried gas at something like 85% or better. the fill tanks has dry 99.99% O2. Every time i see this it torques me becasue at one time I needed a intake filter for my bauer captitano compressor. it looked familiar to ones i used at work. funny they both led to the same National stock Number. bauers was 60.00 and they were at work under 5$. Bought on internet for 7$ after searching the part number..
