I highly recommend the book Asymmetric Politics by David Hopkins and Matt Grossmann. It explains why the divide is as it is.

In short, however, it is as you point out, when it comes to specific policies, most Americans are operationally liberal, which is to say, they support liberal policies. The policies highlighted in this article are, I think most would agree, liberal in nature. The problem is that about half of the electorate are symbolically conservative, which is to say they support the party and candidates that position themselves as conservative. If two candidates are in a head-to-head, they will select the candidate that can display the most convincing conservative credentials. A form of virtue signalling, if you will.

The problem, now, is that one party blocks the other party for not being conservative enough. This is despite the fact that, by world standards, one party is far right and the other is centre-right. There is no leftist party. The far right party have turned "liberal" into a slur with which they characteriose the other party, but most actual liberals are independent - ironically, since the use of the word "liberal" as a slur has increased, more liberals have joined the supposedly liberal party. This has mostly happened since the 50s, but ramped up in the 80s and again in the last decade.

In truth, one party enacts far more legislation than the other, because the latter party is for "small government" and each new law has the potential of increasing the size of government. That is why one party blocks rather than working toward bipartisan agreement. Holding the party in power to fewer new laws can be positioned as managing the size of government; it also means fewer chances for making life better for the electorate, and a disillusioned electorate will always kick the "bums" out.

Of course, the only people that benefit from a reduction of government power are those that have power of other kinds (monetary, religious, etc.). So, whichever party has more religious and corporate heft behind it is probably not working for the people. All they need to do is convince enough people that small government means lower taxes and they remain viable, even though this "policy" is a demonstrable falsehood.