You mean measured knowledge acquired through a every specific way is currency. Someone who acquired the same knowledge on his own will be cast aside until he gets his certificate.
Sure, but why would you hire an unlicensed electrician, or surgeon, or car mechanic, or builder, or elevator mechanic, or really anything that matters?
The only areas where this point becomes moot are in areas where certifications already are not an issue, i.e. in jobs that almost anyone can do.
Also, I’m fairly certain car mechanics are not licensed where I live. Sometimes licenses are just frivolous, especially in modern day society.
You don't need a licensing system, you just need a reputation system. Like how bonds have a rating system; nobody's stopping you buying a junk bond, but the system makes it clear to you that it's a got a high probability of default.
If it is not a matter of life and death, there's no possibility it will happen, because of regulations.
Anyway:
More than 250,000 people in the US die every year because of medical mistakes, making it the third-leading cause of death
10 percent of all U.S. deaths are now due to medical errors