My In-N-Out Theory™ is that west coast ppl grow up w/ v different flavors & simpler/healthier/fresher foods so it tastes good to them (or "us" I should say) but east coast people are used to foods with more sauce/spice/grease so they're obsessed with Shake Shack. Also nostalgia
Totally agree. I don't /love/ their fries but I do appreciate how fresh everything is and I finish In-N-Out feeling better than I do after I finish Shake Shack /personally/. Also appreciate that In-N-Out is like half the price of SS