In other countries 45/55 could easily be a swing state.
For example the 2014 Scottish independence referendum was decided 45/55 and that is usually held to be a fairly close result, at least close enough that it hasn’t ended the question.
So the real story here is voter polarization. The reason that Texas isn’t a swing state is because there’s a big hard core of immoveable voters at either end. So the actual population of swing voters is small.
I'm not exactly sure I would call the current political climate in the US voter polarization, it's an odd framing for what is ostensibly party polarization. You have political conservatives and christian conservatives pulling the Republican party further to the right to the point where libertarians and capital-M Moderate Republicans like Romney, McCain, Fitzpatrick have more in common with Democrats than their own party which would sound insane to anyone in the 00's.
I genuinely don't think that outside of a small minority who drank the Trump kool-aid the political views of the country at large have really changed. The biggest shift is that my friends who were and still are run-of-the-mill "Republicans" don't feel particularly represented right now, and I get it.
With the murmurs of Biden maybe stepping down I think if the Democrats nominated a Moderate Republican they would win in a landslide. It's nuts how much I didn't appreciate having two genuinely good candidates in 2008/2012.
In other countries 45/55 could easily be a swing state.
For example the 2014 Scottish independence referendum was decided 45/55 and that is usually held to be a fairly close result, at least close enough that it hasn’t ended the question.
So the real story here is voter polarization. The reason that Texas isn’t a swing state is because there’s a big hard core of immoveable voters at either end. So the actual population of swing voters is small.