Louisiana is much smaller, for one thing, in both size and population. New Orleans is also a larger percentage of the populace than any city (or combo of cities) in the rest of the state. I mean, come on--Natchitoches and St Martinsville aren't major competition for New Orleans. Even combined with Baton Rouge and Shreveport, they're all still small potatoes compared to NOLA.
Most of the people live in the cities in Texas, but the numbers of liberals in them can't quite match the numbers of rwnjs living in the few blue areas + the yokels who are an overwhelming majority in the less-populated counties.
There are basically 15-20 counties that consistently go blue in Texas: Harris, Bexar, Dallas, El Paso, Travis, Hidalgo, Starr, Cameron, Webb, some of the smaller counties along the border, and now, increasingly, Williamson (suburban Austin) and Ft Bend (suburban Houston).
Out of 254. Do you realize how many people live in those other 234 counties?
For every Dallas or even the not-as-liberal-as-it-brags Austin, there are 10 cities like Amarillo, San Angelo, Sherman, Wichita Falls and Tyler--middling cities that together add up to Dallas or Austin. Worse, those middling cities are far redder than Dallas or Austin is blue. The redness only deepens for the vast majority of the 234 counties that are lucky to have a town pushing 15K in them.
That's why Texas is red. It's death by a thousand paper cuts. Or, more precisely, 234.
Louisiana simply doesn't have huge numbers of mid-size cities and towns and rural areas competing with New Orleans, population-wise. Your state is like many others that have a gigantic urban population concentrated in one area--maybe two--that dwarfs the rest of your state. In VA's case, it's the DC burbs. In Alabama, it's Birmingham. In CA, it's the LA and SF metro areas. In NY, it's metro NYC. And so on.
Texas doesn't have that kind of concentrated population in one area, so it's useless to expect it to perform like other states do. It won't, because it's not structured like other states. And I doubt it can be.
That's why Beto's 254 campaign is the only hope he has of winning in his state. He can't concentrate only on one massive population region and be done with it. He has to hit the road and reach out to the entire state.
By going to each of those counties, he's making contact with voters who usually never--and I mean NEVER--see a campaigning politician's face. Second cousin of mine lives in one of those places. He was so excited to have any politician come to his town that he voted D for the first time in his life--for Beto in 2018. Voters in those outposts are taken for granted. But Beto showing them a little love, letting them see that he doesn't have horns growing out of his head unlike what Fox or talk radio says, taking the opportunity to talk WITH them--that might turn just enough voters, county by county, to eke out a statewide win when combined with the blue urban centers.