I'm not sure in which universe you live but I've met plenty of incompetent and ignorant doctors who gave advice which didn't make any sense.

Same with lawyers and accountants (accountants have so many certifications it borders the ridiculous).

More than the knowledge you've proven to have once, it's important to evaluate ongoing performance and care on the job.

That's something you can hardly prove during an interview.

A market based model of work with a system of reviews would be an improvement in my book