Almost no companies come out and say "we will ask you some dumb bullshit in the interview and not tell you what we're evaluating or how we're evaluating it" and a huge percentage of the industry interviews like this, at least to some degree. The best I've ever gotten when asking "is there anything I should prep for or expect for the on-site, and how's the interview going to run?" is "bring a laptop, here's a schedule of who you'll talk to and what their titles, oh and consider dressing [some way]".