Meno: Please clarify what point you’re trying to convey. Are you asserting that if milk that has no hechshor whatsoever is being sold in the U.S., people who use Cholov Stam would have no problem buying it and drinking it and actually do so?
Some would and some wouldn’t, just like some people wouldn’t drink bottled water without a hechsher.
But my point was that your claim that people who rely on R’ Moshe’s hetter still wouldn’t drink milk without any hechsher is simply not true. It just happens to be that most milk has a hechsher anyway.