[alteriority]

can't speak for gruez, but a couple off the top of my head:

-set standards that all members abide by, potentially bypassing "tragedy of the commons'-style coordination problems

-share information which, in a more cutthroat environment, would be considered "trade secrets".

Not sure how these would apply to the dairy industry specifically; it just seems overly broad to say that price fixing is the only plausible form of cooperation.

[thaumasiotes]

Look into the effects of your ideas, and you'll see them wind up in rising prices. Your first example, excluding industry members who don't meet a particular standard, is one of the most typical forms of "colluding to raise prices" you could possibly think of, often expressed in the form of professional certification.

The only things an economic organization can do are raise prices and lower costs. For a labor union, costs are labor; from the consumer end the workers' "lower costs" mean less work is being done, which shows up as higher prices for consumers.

[jschwartzi]

By arguing from the standpoint of raising or lowering prices you're being very reductive. Doctors form trade associations too, and yes the prices for a certified doctor are much higher, but the quality of care is also standardized and usually higher to match. OP wasn't making the point that industry associations don't raise prices. OP was pointing out that most industry associations are formed to try to make things better. And that might result in increased prices, but that's a side-effect and not the goal.

[elmomle]

Setting standards and price fixing are different things. You can have fair competition within a marketplace with rules and standards. Price fixing is when all sellers agree to not sell below a certain price, which is a problem pretty much regardless of a marketplace's rules.