I will try to answer:
>1. Why there is no consistency for hiring?
Because there is no consistency in humans. Jobseekers lie to me all the time, so do companies.
>2. Why companies have to be so different in assessing values ?
Because companies consist of humans, which are inconsistent, see 1.
>3. Why standardized leetcode kind of problems? instead focus on creativity & unconventional thinking?
That is only a SF/Nyc/big tech thing. Normal firms here in Switzerland (or Europe) rarely do this. The big brand names do it because they can.
Google et al. has a revolving door of applicants, so they can make them suffer. Also, if you show that you can study 3 months for an interview to balance a red black tree, you likely will do whatever the firm tells you to do. You likely will be a good worker!
If you are full of creativity & unconventional thinking, being employed (especially in a big firm) isn't a good bet, start your own firm instead. I did exactly that because I suffered as an employee, not because of the work part, programming was great, but because of the being employed part, and this is how I became a self-employed tech recruiter. Btw. if you look for work or career tips, my email is in my HN handle.