Us Americans have been brainwashed against unions. We have TV shows portraying "the lazy union worker". We have an entire political party dedicated to talking about how unions raise costs, are corrupt, and have burdensome dues. Any shop in the US that starts talk about unions will hire union busting PR firms and shove anti-union propaganda and fear mongering down employee's throats.

Americans hate unions because big business here has been effective at demonizing them.