I've seen that in works of fiction, where it seems to function pretty well.
I have yet to come up with any real-life example that stands up to scrutiny.
Apparently laundry detergent manufacturers kept on increasing the size of their standard detergent bottle without increasing the washing power in order to make it look more impressive on a shelf. This caused an "arms" race in detergents.
WalMart stepped in and refused to stock detergent bottles past a certain size. At that point, the manufacturers stopped making the large size bottles.
If there's a player with as much power as WalMart then they can dictate pretty much whatever they want - and sometimes their interests are aligned with the customer.
All in all, not at all unlike how government protection agencies work, but in this case entirely private and independent. The neat part is that, IIRC, their safety standards were mostly stricter than the US.
Probably the exception to the rule though.
The American Dental Association is another example. I do look for ADA-approved toothpastes.
[1]: http://www.ul.com/global/eng/pages/offerings/perspectives/co... [2]: http://ulstandardsinfonet.ul.com/scopes/1083.html