When you start probing enough it quickly becomes practical/coding interview we all come to detest. Sure enough, that way you might not even need 30 minutes. But shop talk alone doesn't cut it.
Maybe your “shop talk” is different from mine, but I can suss out fakes from the first sentence usually. You’re correct in that they go straight for the broad architecture strokes, and they speak in vague terms. Trying to get a solid grounded answer is like trying to nail jelly to a tree. That’s when you know they just read some wikipedia articles and don’t know the practical applications of the words they’re using.
There's a number of people with CS or SW engineering degrees who can't actually code. Those can often quote you Gang of Four patterns, discuss broad slices of tech and draw architecture diagrams on the board. But still can't code.
I know, I work with several. I’m pretty good at spotting them because I studied them while working with them. Fun fact: if you poke in the right places, you’ll see that they don’t even understand GoF and architecture, they just regurgitate the what they memorized.