Because America has a first past the post election system, which will always result in two dominant parties. See https://m.youtube.com/watch?v=s7tWHJfhiyo for an explanation.
This is an important part of it. The other part is the fact that success in politics is very hard without money, and most rich people aren't progressives.
In no country in the world is the progressive party the main attractor of wealth. Progress means change that will lessen the comparative advantage of the wealthy.
Tired of this whole "America is conservative to the rest of the world" thing. No, it is conservative compared to Europe, specifically. I don't mind making the comparison. But the arrogance of equating Europe with "the world" frustrates me.
California is extremely progressive compared to Russia, Saudi Arabia, India...just not, specifically, compared to western Europe.
But is that a cause or an effect? Because there are only two viable parties, all the money gets pumped into those. To get on equal footing with one of these parties, one would need a lot of money.
With say a dozen parties, the money would be distributed more and thus the total money one party has would be much less.
But then again, it's the US, the first past the post thing is only part of the problem. The corruption on all levels of politics and government is a much bigger problem. Even with a dozen parties, all the money would be poured into the party that favors the rich. And saying that's legal and not corruption is only a sign the lobbiests have been so successful, they've made the corruption legal.
With capitalism money will always rule the world. Whilst this may have sounded great right after WW2, in reality it has caused the rich to get richer at the cost of the general public. It has caused mass consumerism to explode and destroy the planet, buying stuff we don't need. Shipping stuff across the world, because it makes the most money that way. To move issues of slavery, safety and pollution to parts of the world the buyers can't see. So people can pretend to live in paradise for one or two generations, whilst ruining the chances of future generations. Investments in sustainability have been slow due to the impact on the bottom line. Can't have people using the same durable repairable stuff for decades, they must buy new shit every year and be programmed to think this is a good thing. Why invest in clean forms of energy, that's expensive, just do the cheapest thing possible and then try to make it cheaper so we can make more money.
Long-short, it’s known as Duverger’s Law. Winner-takes-all (single member district majority) incentivizes competing interests to consolidate power into a unified party label to increase chances of winning. Any third party necessarily steals votes from one of the two main parties, which is why each party manages its label for maximal policy coverage and every issue becomes red vs blue.
No corporation wants to support a progressive party. No one profiting from corporations want to support a progressive party. There goes 99% of the wealth in America.
You have similar results in less capitalized countries.
In Germany half the seats in the Bundestag are filled with district representatives that are voted for in a FTPTP manner. These seats go almost exclusively to the largest two parties. These two are the big center right and center left parties.
A cause, what capitalist would support a party that will decrease their power? There's a return on investment if they support the republicans or democrats.