I'm sure most of the result is driven not by consumer choice but by corporate choice of where they choose to locate based on target demographics and real estate availability; as well as where regional chains start. For example you probably won't catch too many liberals at Krystal. Only two that stand out to me as consumer choice deciding the political flavor of a chain are Starbucks and Jesus chicken. Sbux because liberals like pretentious coffee and CFA because liberals hate them. And I like their wi-fi, chicken, and lack of patchouli.
Had no idea until 2am Saturday morning that Cook-Out was a christian chain, pretty obvious I suppose if you have bible verses on the cups, just never noticed. What 'til the moonbats find out.