How many 100% self taught, no prior experience people are applying to these positions and are accepted for interviews? Obviously that number is extremely low especially given the last couple of years.

Having a process which only exist for the 1% of least likely candidates is absurd. Even if you wanted to give these people w chance, obviously you don't need to subject the 99% of people to the same process. What is the point of asking a CS graduate with 5 years industry experience some brain teaser questions? There is literally no point, it tells you exactly zero about the candidate.

Also, you can self teach everything in most engineering disciplines. What part of Electrical engineering or mechanical engineering requires a substantial financial investment or has things you could only learn in a university?