Well, partly because of people being genuinely unaware. This is the silver lining of Trump being so mask off and people need to leverage it for education as best they can, whether they are in the US or somewhere else where educating better about the US can still have value for shaking off imperialism.

As awareness, I'd say there are two main types of liberals in the US. There are the consciously-liberal types who are aware of how things work, that liberalism is a tool of the power elite, and they intentionally use it to try to block and absorb revolutionary energy. These are the Biden, Harris, Clinton, Obama types. And on a smaller power scale, the sort of people who organize the democratic party machine from the top end to make sure it stays in the limited corporate form it is. Then there are the liberals who are like "live, love, laugh", who haven't really confronted the cognitive dissonance of them espousing pacifist beliefs while also not being out there objecting when their country is in constant wars. This group can more so be persuaded and moved. It's just an uphill battle against decades of anti-communist, pro-imperialist media and culture, and any material benefits they're directly or indirectly getting from that. But now is a great time to be trying, when they are getting pissed off at the developments of the status quo.