More broadly, I think you're confusing "non-discriminatory" with "equal chances". A blind audition doesn't mean all participants have equal chances of success. Someone who's been playing the violent for 25 years is probably going to have a better shot than someone who has only a few years of experience - and the lattice has better chances than me, who has zero experience. The fact that we have unequal chances of landing a spot in the orchestra isn't evidence of discrimnation. It's the system working as intended: the more skilled musician has greater chances of getting a spot, regardless of factors like race, gender, etc.
In the context of tech hiring, the purpose of the hiring process is to confer greater chances of success for candidates with relevant skills and ability. If someone is hiring for a position demanding C++ experience, then candidates who are C++ wizards are more likely to succeed at this job opening than people who occasionally dabble in C++.