Try to get money from miners is a fail - they'll just shove them into OTHER ISP options, since we don't NEED high-speed Internet to mine with.
The ISPs are far more worried about the impact of HIGH VOLUME USAGE stuff that forces them to spend money for infrastructure upgrades - which have a MUCH MUCH HIGHER impact on their bottom line than trying to get a few $ out of "miners".
Also keep in mind that outside the "3 cheap electric" counties in Central Washington, miner density is LOW in the US - there aren't enough "miners" using most ISPs outside of this area to make it profitable to TRY to chase forcing them to pay more - and there are MAJOR legal issues with the whole "special fee just for miners" concept that will probably COST an ISP that does that sort of stupid thing a ton more than they could make from it.
You are ignoring the small detail that in many places there is no competition. What other ISP options? I can choose Comcast or no Internet. I agree it is highly unlikely that ISPs won't go after miners, but the reason is not that "they don't generate traffic so we'll leave them alone" it's "I see no way of getting a fuck ton of money out of them without getting into too much trouble". Nothing good comes out of private companies securing monopolies.