I used to work in one of these kinds of stores for a long ass time and this is what I figured out about the whole thing.

When it comes to books that are soley about current affairs rightists will buy a much wider selection of titles, but books that appeal to libs and leftists sell more copies overall. It's part of the rightwing grift for dudes like Ben Shapiro to publish a book every so often to launder their image as an intellectual and make some money while they're at it. They function more like fan merchandise than they do actual serious collections of thought since they usually deal with VERY current affairs and become totally irrelevant in about two to three years if not earlier.

Books that are politcal in nature that appeal to the other parts of the spectrum tend to show up in other sections and don't sell well next to stuff like you're seeing in that endcap display. In my store Marx was filed under philosophy, books on racial justice were found in social studies, and climate change was found closer to nuclear physics than it was Mark Levin's current ragebait cashgrab. So it's not really that rightwingers are better read, it's mostly how the bookselling industry works.

That being said... in half a decade I had probably 100s of requests for rightwing books ranging from Rush Limbaugh shit to The Protocols of the Elders of Zion (side note, I would explain what it was to people and the reaction was usually something like "what? [Insert relative here] is trying to get me to read THAT?" so Im pretty sure I started some fights indirectly) and exactly 0 requests for Marx or Kropotkin or anyone like that. However books about racial justice, womens issues, queer matters, and the exploitation of labor sold reasonably well on their own.