Look at it this way. Here in the Colonies, the US DOT writes the rules about pressure vessels that are or may be transported across state lines. So there's this "DOT blah blah" number stamped in your tanks, right? And the DOT sets the rules for the hydro test that your tank gets every fifth year, right?
The DOT's official hydro test procedure, echoed by the CGA (Compressed Gas Association) dictates that the first step in every hydro test is a VISUAL INSPECTION OF THE TANK. That's right, if your tank was hydro'd, it was not hydro'd until after a VIP was done. So legally, a freshly hydro'd tank does NOT need a totally redundant VIP by your local SCUBA shop. The shop will tell you that hydro guys don't know how to do a VIP on a SCUBA tank, they're not competent to do it. Ergh...but you'd trust their hydro competency?
FUD. The industry is full of Fear, Uncertainty, and Doubt. They create it so they can sell what you don't need, like a $40 "VIP Plus" on a freshly hydro'd tank.
I know some SCUBA shops that refuse to accept a VIP done by some hydro shops, because even though the hydro shop is DOT licensed...they undercut the SCUBA shops by dealing directly with the public. Oooh, isn't that terribly dangerous?
So each shop makes their own decision, can they look up an inspector number? Is the sticker from a shop they know? Does it look home made?
Yeah, a real VIP *is* a real matter of safety. But what we have here, is FUD. FUD and profit.