Even abusive crawlers and scrapers are acting as agents of real humans, just as your browser is acting as your agent. I don't even know how you could reliably draw a reasonable line in the sand between the two without putting some group of people on the wrong side of the line.

I suppose the ultimate solution would be browsers and operating systems and hardware manufacturers co-operating to implement some system that somehow cryptographically signs HTTP requests which attests that it was triggered by an actual, physical interaction with a computing device by a human.

Though you don't have to think for very long to come up with all kinds of collateral damage that would cause and how bad actors could circumvent it anyway.

All in all, this whole issue seems more like a legal problem than a technical one.