According to the heter for Cholov HaCompanies/Stam, you should not need any hechsher whatsoever to use non-certified milk in the United States. You should be able to freely drink any American milk even with no hechsher at all. The heter says you can simply rely on the US government and the FDA.
So why don’t user of the Cholov Stam heter use any Cholov Stam milk or products that has no hechsher?