FWIW, most FAANG employees seem to admit that if they had to redo their interview, odds are they're more likely to fail than pass. Goes to show how much luck is involved in the process.
I think it's gotten harder too. Maybe in the past it really was about trying to see how the candidate thinks and solve problems. But now it seems like all all of that is secondary to getting the optimal solution. Two of my friends in Google who got in ~10 years ago say that it's definitely gotten harder from what they see.
I believe they mean e.g. "tell me what happens when you type https://example.com" in a browser.
You can go deep into tcp/ip, dns, how ssl encryption works, how urls on a server get mapped to specific ports, load balancing/round-robin etc.
That could be trivially fixed tomorrow, either by universities or (better) by an accredited certification body.
I mean, I'm sure there weren't bar exams for lawyers and professionals either, at some point in history. What prevents us from creating one for sw developers? As long as it didn't require additional attainments just to sit for it (i.e. you should not need a university degree), it would make the whole process more efficient for literally thousands of companies.
In software it's not like that. There are very few laws on the book about how to write software, so there's no single authority that defines the right answer or the scope of reasonable questions. It's far more open. Even just picking a set of programming concepts would immediately cause controversy. Like, should monads and type-classes be a part of the professional qualifications? Most programmer would say no, because Haskell isn't widely used in industry. But CS degrees do sometimes test people on that sort of thing!
(Also, in both cases, the government hires members of the profession to define the standards.)
I'm convinced we could have a bar exam for software engineering, but I'm not at all convinced that we should. It would make my life easier personally, but it would keep a bunch of people who followed less traditional paths out of the industry and I think that would be bad.
I'd guess 99% of engineers never have to do CS trivia as part of their day-to-day job.