Well, it already is.
The U.S. works on a world milk price, so their solution to low milk prices is to add more cows. Their solution to having access to high milk prices is to add more cows. What that means is increasing production. It's not a good formula for their producers from an economic standpoint.
The producers I talk to in the U.S. would love to have the type of system we have here in Canada, because it controls production and it is also a guaranteed return on investment for the farmers.