edit: I didn't mean to sound like I was trivializing your experience. The "culture fit" is really nasty and sucks for everyone who isn't "the norm".
Perhaps focus on rapport at the start of your interviews?
I don't think that is the issue. I was looking for an entry level position at the time, it's a CROWED field, and the handful of places where I and another much younger classmate both interviewed where I could compare included at least one, often more phone interviews. If I wasn't getting along well with them I don't expect they would have brought me in. Most of the phone calls and interpersonal in person interviews went great IMO.
To be clear I have no idea what their idea of "culture fit" actually was.
I've since started asking, nobody has been able to answer without first looking confused and humming and hawing a while. Most of the answers were usually surprisingly generic and such about "openness", "fun" and such, I suspect a few were made up on the spot. Amusing ;)
Welcome to the "culture" wars.
If you had been hired in those companies, you wouldn't have lasted long. Unless you have a supernatural talent on filtering out bullshit.
I did a handful of interviews at places where folks who I went to school with also interviewed.
I got a lot of "culture" questions. My younger classmates, did not hear the world "culture" in their interviews, ever.
It's hard not to be pessimistic and assume "culture" was about age...