Also, I would also be quite surprised if Google didn't allow candidates to Google information during the interview...
I did a Google onsite several years ago (probably 7 or 8 years ago at this point). Each interview was just me in a room with a whiteboard and a person sitting at a table across from me with a notepad. No computer present.
I suppose I could have dug out my phone and Googled, but that feels unprofessional to me, moreso than if I had access to a computer.
Also the part I got stuck on was coming up with the trick needed to solve the problems. Most I was fine, but one in particular would have taken some decent searching to find something equivalent if I just Googled, and would have taken some time to grok the answer. Also that guy was not very forthcoming with hints or information when I asked him, so I doubt he'd have appreciated a Google search.
I don't remember the exact question, but it had to do with converting a 3D city model into a 2D skyline by drawing a single line. I got stuck on trying to visualize how to deal with partial overlapping models and irregular building shapes and ran out of time.
It's like a dance. Your are supposed to lead deriving the solution, interviewer is supposed to follow closely and judge your performance.
If you expect to ace an interview just like that then you also need to be lucky not accidentally getting asked to stuff, which you always need to Google an answer to, basic algorithms and patterns, which you usually kind of know but could slow you down during the precious 40 minutes you have to show off your skills.
And lastly, people do prepare for these. If you do not do that, you might simply make a slightly worse impression than someone who did.
That being said, I mostly did not prepare for the coding interviews. I focused on the design and behavioral interviews.