I happen to agree with you, but it's also worth mentioning that solving whatever problem is creating the need to post ghost jobs in the first place would also make posting them unnecessary (presumably insecurity about the company's ability to assess, hire and retain high quality talent.)

But those are very hard, company-specific problems to solve, hence my agreement :-)

Sometimes it's sending false market signals: a company that's hiring must be doing well, right?

Not really. Make posting fake jobs illegal. Strengthen some whistleblowing laws. Watch as it stops.

Maybe official 'name and blame' service where anybody could post their experience under their real name?

It's a multiparty problem. I really wouldn't want to post negative experiences of companies under my and their real name while still looking for jobs elsewhere.

Glassdoor could only possibly be accurate because it was anonymous. Of course, that also makes it easier to fake.

It'd actually be easier for a government app to verify identities and (especially if mandated by law) protect your anonymity.

The private sector is great at lots of stuff but running a clean marketplace isnt one of them - the incentives are off.

Unfortunately, in America, at least, that would be likely to lead to a lot of lawsuits—lawsuits that should be shot down under the SLAPP category, but it takes enough money and time just to respond to a lawsuit that many people would be unwilling to take the risk by posting anything.