A guy who was my next door neighbor for a number of years had spent his entire working life in the tape division of 3M. At the time we were neighbors, he was the production manager at one of 3M's plants. He was a real wealth of knowledge on most any sort of tape they made. This was a number of years ago, so at that time the beige masking tape was the only autobody masking tape 3M made (except for the fineline tapes).
He said the main difference between their regular masking tapes and autobody tapes was a heat treatment cycle that stabilized the adhesive. This treatment was the reason the autobody tape wouldn't get welded to the surface by short term exposure to the heat of the sun or the heat of paint curing lamps or ovens, while their regular masking tapes would weld themselves in place in the same exposure much the same as any dime store masking tape would.
When I asked him why the autobody tapes were so much more expensive than even their own non automotive tapes, he said there were multiple reasons. The autobody was considered a specialty tape, which automatically meant higher pricing. Next, the volume of autobody was only a small fraction of total masking tape production, further increasing the price due to the much smaller comparative volume of production. And finally, autobody supplies of all types are extremely high profit margin goods at the retail level, as compared to seemingly similar products retailed by general merchandisers.
Another thing he mentioned is that autobody tapes have a definite shelf life, and that's why there's a date code printed on the inside of the core of every roll of tape. He said anytime you run across a roll of tape that seems difficult to peel off the roll, chances are its old and if you use it you run the risk of it welding itself to the surface just like a roll of hardware store tape would do, or not adhering properly at the edges and resulting in paint wicking beneath the tape. Obviously, neither problem is something you'd want to risk for the price of a roll or two of tape.