> I find it interesting that a substantial number of people seem to think it's wrong or unethical to cold-email someone about a potential recruitment or business opportunity if they post their email in a public place

I find it interesting that some fucking spammers think that just because they found out my email somewhere, they should be allowed to waste my time and resources for their shit.

That is explicitly illegal here in EU. Unless I have clearly given you my consent, you are not allowed to spam me. Is informed consent really such a difficult concept to understand?