How can you be sure that the YouTube is right and real life professionals are not? Making money on YouTube ad revenue share is quite popular thing today, and no one verifies what is uploaded there, unless it is a copyrighted material.
The contractor just needs their work to fail not-before the warranty period expires.
Think of them more like foreign software contractors being paid per JIRA ticket, rather than in-house long-career developers.
That's a very valid point. The question is who has more skin in the game. Contractors have more of a positive feedback: if I am satisfied, I will recommend them to my friends and relatives. YouTubers may have more of negative feedback (not that much since dislike button is gone), but it takes someone to call their bullshit and write a refuting comment. I don't think lots of core YouTube userbase is inclined to do so, the default behavior there is to make a "pffff" and swipe away.