"Alternative" products like duck eggs, water buffalo or goat's milk, etc. do not count, so there is some room for market diversification there, I guess.
It has the net effect of keeping dairy prices at what's seen as an acceptable stable level that also keeps dairy farmer's in business, at the expense of diversity in the marketplace and access to new farmers.
I think most Canadians feel that the supply-side management of dairy and some other food products works for us fairly well, and that the Taxi license system doesn't. I guess that means the reasons for them working well or not are something other than the concept of supply-side management?
When you go making your own homemade cheese or yogourt though, then you notice how painfully high our (consumer) milk prices are. And when you taste higher quality milk in European countries, and notice the lack of quality milk at reasonable prices on Canadian grocery store shelves, it starts to be a bit more frustrating.
Quality here is not a function of the market being more free.
It's a function of a better food production chain
Instead of competing on prices many food products in Europe compete on quality and locality (small areas that produce some unique product of extremely high and renowned quality: Champagne in France, Parmigiano Reggiano in Italy, jamon serrano in Spain, etc. etc.)