Consulting firms that don't do case interviews?

Hate to break it to you, but there really aren't any. 

I've spoken to boutique shops, economic consulting, operations consulting, the traditional strategy shops, Big 4 consulting arms, IT consulting, and pretty much everything else, and the truth to matter is that a typical interview process, even at the internship level, will involve at least one robust 45 min case and one 5-10 min case.

Actually, jogging my memory a bit, there was exactly one firm that provided an offer after only a fit/behavioural interview for an internship position. When I spoke to other interns, I realized it was an outlier and that the employee who interviewed me had left for vacation. 

I’ve heard some of the boutique firms sometimes forgo the case interview for my traditional behavioral / fit interviews. However this is really rare.