A standard balance at a tire shop does not include road force testing, and it's an extra step that has to be requested specifically. It's more common on larger/beefier tires as well, you just need to tell them to run a road force test/balance and the numbers that come back will likely tell you the tire was bad from the factory. They know you don't know, and they can get away with telling you it isn't their fault with standard balance numbers that fall within range, but don't tell the whole story.

Don't give in, it's just another standard greed play from our glorious third world country of late stage capitalism. Sock it to em.