But that 2 weeks means you've told other candidates you're not interested, taken down job postings, you have to go through all the paperwork to establish them as employee (tax forms, insurance, that stack of onboarding paperwork), and have to pay severance if you fire them. And you're out those two weeks that a non-fraudulent employee could have been productive.
Now you have to re-open the job-listings, re-screen candidates (some of whom you might have to apologize with a "we're sorry we rejected you, but the person we thought was better turned out to be a fraud"), and do all the onboarding paperwork again.
So there's certainly value in determining fit up front.
I wish I had a good answer from the candidate side of things. I do contract work so it's very different from trying to get a traditional W2 (or whatever the equivalent is in other countries) job. For me, most work I've gotten has come from either knowing somebody who can get my resume in front of the right people, or from my publicly helping folks (mailing lists, Reddit, fediverse, formerly-Twitter, utilities I've shared on GitHub, and my blog).
And the AI rubbish is bidirectional—inept AI-assisted candidates applying to positions, and inept AI-assisted interviewers/HR systems ingesting the firehose of applications. The whole landscape is 💩