were they a bad employee? did they sneak in the door at the last place? Is there a problem with how we do interviews?
So as a hiring manager I am pretty OK with rejecting a lot of good applicants just because some little part of the interview didn't go well, if it means that I never hire anyone really bad. The good applicants will get jobs somewhere else, it's OK.
The technical interview is part of that. The coding test is part of that. Sitting down with them and making sure they can talk through a problem with their future teammates is part of that. There's no one piece.
And finally, if your career is to write code and solve problems, and someone gives you a test where you have to write code and solve problems, you should be elated. Is there anyone that wants to answer the "Tell me about a time where you had a disagreement with a supervisor"-type questions that the rest of the world has to deal with?
How does this square with the oft-repeated "shortage of engineers" meme that Silicon Valley can't shake. You seem to be able to pick and choose, and pass on good candidates for nit-picky reasons, so is there really a shortage of talent?
3-6 months to get someone trained up, and a lot of their pay would be in /training/ them (you'd still pay at least a living wage for the area, but you might upfront plan and disclose to relocate them if hired).
The benefit would be both in seeing if they're a good fit, and also enriching that employee as an employee. Both sides would have a much better perspective of if it's a good fit, if they want to restart the process with a different team, or if the employee can find better value in society elsewhere.
The problem with apprenticeships is that educators are handing over a large part of your training to a company with unknown factors, like mental people with random hangups. Still, I'm sure many of us when we got our first job felt hopelessly unprepared for working in a real company.
Some companies are smarter than this, but most are not, from what I've seen. So yeah, they're going to worry about poaching because they know they aren't doing what's really needed to keep people.
The cost seems much higher to me. I have to interview dozens of people to find a single good applicant. Rejecting one good applicant costs me dozens of interviews, not one.