Fake job seekers are flooding US companies that are hiring for remote positions

Solution is extremely simple, fly the candidate out for an in-person interview. A one-time plane ticket is a tiny expense compared to paying for the company to be a fully in-office operation, or paying a fraudster's salary.

Onsite interviews were a normal practice just a few years ago.

I agree, but as a non-American I wouldn't want to travel to America for anything work-related at the moment without a business visa, and the hassle of getting one would make hiring foreign workers much more of a chore.

So many visa and proctored exam consultancies in India and I never heard of any of them verifying interviewees for remote jobs.