I've noticed that In-and-Out Burger seems to have a more devoted fan base than I would expect for a burger and fries joint. They're not in my area of the country, so I can't just go out and try it. But I will visit California again some day. Convince me why I should stop there, especially for someone who really tries to avoid fast food whenever possible.
In n Out was a Cali region favorite that established themselves for standout quality, strict adherence to being on brand, stoking a bit of nostalgia, and building a local following with gimmicks like the hidden menu. They established themselves in Cali, and by resisting expansion, it became kind of a 'cali only' thing locals attached to as 'theirs'. This was before boutique and gourmet burgers were all the rage everywhere else. This made it kind of a 'destination thing' to do when in Cali and the legend grew. They eventually grew through the southwest and into Texas... but again kept themselves more of an exclusive... and differentiated themselves from the Wendys/McDonalds/BKs that dominated the scene. They built their following that way. It was a combination of 'unique'+quality promise+service differentiators... boosted by a possessive cali culture. A great product strategy. They are also well respected in their markets for their approach towards employees and community. So they are a liked brand.. instead of an evil corp.
Now the the prime menu differentiators they used to stand out... fresh toppings, quality unfrozen meat, and diverse menus have been duplicated all over the place with other gourmet burger chains. The market is flooded with chains that try to offer a premium burger. So someone who has had Five Guys, Smashburger, Whataburger, Fosters, or any other of the 3 dozen plus burger specialty places at their doorstep for the last 10+ years goes into a In n Out Burger for the first time and goes 'meh... good but not a standout' simply because they have no attachment to the aurora around it or see it as much of a unique offer because they are surrounded by 'like products' all over now.
Still a great product and good company - but one whose product differentiators have been hacked away at by other more boutique burger brands now. Anyone who wants a specialty burger likely has multiple options now... not just 'fresh vs fast food'
As to why someone should go there... it's meant to be a throwback to service and a quality, fresh product. They make a great burger and have classic shoestring fries.
Because you stated "It’s so simple that you’d think other companies would figure out what work"
The point was as stated... a good portion of that success is hard to replicate at scale. And what is scale in that industry? Let's look at the competitors... and the kinds of companies that have not figured out how to replicate their success in their own product. Hence why someone would 'compare them to other companies' when someone postulates why 'other companies' haven't figured out how to duplicate their success.
Uhh... no one said CFA wasn't successful nor that no one noticed.
The whole point was 'knowing' or 'taking notice' as you hinted to isn't the problem for competitors to learn from CFA. It's that you can't take a McDonalds and simply say "do what CFA does... ". CFA's differentiators are built into their operations and management mandates and it takes a firm hand and commitment to make those things payoff.
Everyone is aware of CFA's success and their differentiators. The challenge for other companies is to either counter them or decide which they should embrace themselves.. even decisions like deciding if some image 'borrowing' or refreshes are needed.