Had they been able to let the market set the price of milk

They do that in the US. Farmers sell their milk for under production cost and then beg the US government for billions in handouts and every politician, liberal or conservative, is more than happy to throw money at them.

And let’s also start buying American milk, if we fuckin want to.

If the US government stops handouts to US dairy farmers, then I would support it. If they don't, it's not a fair market when they can sell below productions costs.