I think because the USA culture is pathological in generally letting people fend for themselves rather than helping them, at least at the level of government. In this case, individuals like you and me supposedly have freedom of choice against the economic far west dominated by big companies, who by the way are also allowed to "lobby" lawmakers. I think this absolutism about freedom of choice, which in practice is largely illusory, is deeply ingrained in the culture. Therefore it's ok if companies are dishonest, they're just using their freedom of expression. It's really stupid, it's also a foundation of right-wing thinking all over the world. It's almost inextricable from the American Dream.