A Reason Behind In-N-Out Burger Success

One of the closet competitor to In-N-Out burger is Five Guys burger, even though, this comparison is not fair at some point because Five Guys stores are all over the nation, unlike In-N-Out, which is generally located in California, but with all that, it is known that In-N-Out is taking the lead on that success path, so why is that?
In-N-Out menu prices did not change much since their opening, and this is probably because of their limited expanding strategy. According to Rick Paulas from KCET channel, the price of the In-N-Out double double was $2.50 in 2001 and jumped to $3.45 in 2014(depends on location). 
CHECK THIS OUT!

When comparing prices of similar products between In-N-Out and Five Guys, it makes us realize a bit why In-N-Out is so successful. They do not charge a lot and they provide the best burger quality as well as taste, as of what most people would say.