Response 2: a few sites are already popping up messages asking you to turn off your ad blocker, which is at least a partial existence proof.
Response 3: if you want to know whether I got your ads, use cookies or make the request url unique to me, and then check that your ad servers served the appropriate requests before allowing your content servers to serve me content.
But seriously, I shouldn't be required to solve all these problems for you as a user in order to not be called a thief. If you want a more explicit contract, then require a log in. If that adds too much friction, invent a better a better solution.
*Edited to remove the inflammatory suggestion to go out of business if you refuse to negotiate.
Sounds like the type of negotiation the mob engages in. But, hey, as long as you get what you want, I guess it is ok.
I don't think it's right that publishers seem to view me showing up at their front door as carte blanche to abuse my network and system resources to the full extent that JavaScript allows. And I think it's wrong to characterize user pushback as theft. Other kinds of "theft" are criminal behavior. Pick better terms.
Adverts are non-consensual hijacking of users resources, so you could argue that advertisers are committing theft. You're welcome to use a paywall on your site, or hide content from people using adblockers if you want to negotiate from your side.
"What header does your browser send to my server informing me that you are blocking ads so that I know to deny you my content?"
1. "Did you just make it up?" -> No.
2. "Which ad blockers provide for that header being sent?" -> Use a plugin in Firefox to set custom headers
3. Do website honor my header? -> Not yet.