John - for a period of time I worked for a large, multi national chemical co. in Charleston, WV. This particular facility made MASSIVE amounts of ethylene glycol in addition to aircraft de-icing fluid. I would have to answer your question in the affirmative that there are probably only a handful of companies that produce this stuff. The ethylene oxide (raw material for ethylene glycol) is the nasty stuff that a lot of companies do not want to be bothered with having to handle.
Personally, I use the MB antifreeze because it is really not that much more expensive.
Jim
'95 E320
'97 Honda CRV