Hmm, there's an interesting one.
So it seems that the '"naming convention" between EU (or rest of the world) and US about tank volume is different too.
We call the size of the tank exactly what it's volume is when filled with a fluid (which is non compressible) so you instantly know/can relate to the actual physical size of it
So 6 liters is actually 0,211 cubic feet (or 1.58 USG)
97 Cu ft equals 2746 liters. Which is an impossible number for a Scuba tank.
So it seems the US market calls the tank volume NOT the real tank volume but the pressurised value. (possibly to make it look more impressive, as you get a much higher number.
But besides being bigger it is really a totally useless number by itself alone, as you now need to know ALSO what the max pressure is the tank can handle so then you first have to make a calculation before you have an idea of it's REAL size.)
Like in your example of the "great white": if the fill pressure is max 200 bar (3000PSI) it's real size is nearly 15 liters. (2746:200=13,73 liters)That equals to a BIG Scuba divers tank.
But if the max fill press of the "great white" is 300bar (4500PSI) the real volume is 2746:300= 9.15 liters. And that is what mostly consider as a regular scuba tank size.
So there you go, another point for the metric system...(but don't worry the USA will NEVER switch, the building contractors sabotaged that years ago)