Re: "crypto mining software is not malware"
"If I put a notice on my site saying you agree to pay me £10 on landing on the page and £10 every minute you stay on the page (ignoring practicalities of collection FTM), and you have no way to know that until you visit so I’ll always collect £10 from people enticed to my site, IANAL but that seems unenforceable as a contract."
Absolutely, but in this case what is being taken isn't cash but CPU cycles. Maybe not that many people are explicitly aware of it, but having a website execute code on your computer without your 'a priori' knowledge of the details (and taking the visit to the website as implicit consent) is the way the internet works. That's why one should be wary about clicking on random links to unknown sites.
It's true that the code being executed is in the website owner's interest and not yours, but as the article points out, this is literally identical to what ads / trackers do (actually worse, since this guy had a notice on his website that he's using the crypto mining software, while trackers are invisible).