But scammers don't cost anybody money - and by anybody I mean nobody important, just the plebs.
There's no money in going after scum that skims off the plebs, that's what the government does anyway. And these scammers don't even dent the governments' share since getting had by a scammer is not tax-deductible.
So no, nobody is going to spend good money going after scammers. Not for the money.
One day, we might get ISPs waking up to the fact that their customers are getting fed up by the email bombardment, and, for quality issues and service considerations, they just might think to filter a bit and block scam mails that they can detect.
But it'll have to become an important quality issue for an ISP, forcing them to use it as a commercial argument for better service to attract more customers before we, the plebs, see any change.