I am sure liberals write books too, but never get greeted by a book written by a liberal right there up front in the attention grabbing top billing front row shelves.
Oh, sometimes the lib books are there and sometimes the conservative books are there. You probably notice the Conservative books, because they ruffle your feathers. And the lib books catch Conservative attention, because they ruffle Con feathers.
Of course, that's not true for everyone from either side of the political spectrum. Me? I just go look at the stuff I want to look at. In fact, lately, I've been shopping at Amazon.com more than at physical bookstores.
If you're feathers are ruffled upon walking into a bookstore, then a sales associate somewhere has done his or her job.