Absolutely. I mean I remember 20y ago when someone's solution to spam was paying a small fee. Not what you want, but it's gotta be somewhere there. There has to be a cost to it, but it probably shouldn't be directly monetary. Submission delay might work.

Requiring applicants to pay a fee will mean that the positions that I have to apply for that either do not exist, or are opened "just in case", or are market research, or the COA positions to push internal candidates, or any one of countless similar positions, will require me to pay out of pocket. Not exactly fair from my perspective.

Agreed, while paying to reduce spam may work in other contexts, in this setting the incentives don't align. Imagine if Linkedin got paid every time you applied for a listing, the pile of ghost jobs would be practically infinite.

Some of the listing services actually do charge employers per applicant, unless they are rejected within a certain amount of time (usually 48 or 72 hrs).

The critical distinction here is that the employer pays, not the applicant. This direction works, that's roughly how all job boards work if you squint, but if it was the applicant paying, the incentives would be opposing.

This system still does incentivize the board to accept (or at least not deter) junk or fraudulent applicants.

Isn't this Musk's solution to stopping Xitter spam? Promote subscribed accounts more, so it costs money to speak.

Isn't a better solution to create a reputation score just for email addresses? You start out very low, and sending emails further lowers your score. However, every email that is read (and not marked spam) increases it a little more. If reputations start out just marginally above the "straight to spam" tolerance level, then spam accounts can only get out a few emails.

And you can create a new address for every spam message you send and never get blocked?

How do they contact you? Email, social media, or LinkedIn? If LinkedIn, it is definitely not free. Recruiters pay a hefty fee for the right to contact people outside their network.