So until that's changed, I find it hard to see how we could standardize developer hiring. My coworkers and I all wear a different amount of hats with varying competence. The number and variation of certs required would be rough! "I'm level 4 backend engineer with level 3 data design [streaming level 1, traditional ETL level 7], level 1 hacky frontend dev, and level 2 devops" - sheesh, now I'm spending my whole time keeping those up to date.
There's no "industry-wide Leetcode fizzbuzz portion" - Leetcode and fizzbuzz are famously on complete opposite sides of the whiteboard spectrum! I've only been asked actual fizzbuzz once, and can't immediately think of any other duplicate whiteboard problems I've seen either. Many of them aren't ones I've seen on Leetcode, and would probably be on the "easy" scale there if they were there.
I couldn't pick out any single problem that would make everyone at all my last few jobs happy, let alone the whole rest of the industry.