Back in the day, if you wanted to go out for a burger, you pretty much only had McDonald's and Burger King. Sure, you could get a burger at plenty of other places, but they were just different.
Then along came Five Guys and Shake Shack and Smashburger and their variants. And of course if you were on the west coast, you had In and Out and the like. Now you have more of the midwest dairy style, like Culver's and Freddy's.
The primary driver here is certainly the burger - it's something like the smashed style of Smashburger, being that it's not large - but even better is that you can get custard too. And at Culver's, you can even find cheese curds. Nice.
When it comes to the burger, you can get about anything you want on it, and when it comes to desert, it's about the same. Just make sure you order it on hold - that way you don't have to sit there waiting on it for later. You get a receipt that you simply hand them later and they'll make it for you when you're ready and you can eat your burger (and curds) while it's hot, and you get your custard cold. Best of both worlds.