To be precise this excludes 75% of all autonomous systems in the world, which is at least 75% of all ISPs plus those that connect to 25% of IPv6 capable autonomous systems, but still don't use IPv6. So we are talking like 80% of all ISPs in the world.
No, most ISPs don't. In fact they are afraid of the transition, because of the many glitches, the total lack of support of MANY devices on the consumer side, retraining helpdesk, and so many more.
I work for a large ISP and we've done our tests. We ran one about five years ago and it was a total disaster.
We're currently doing another one and we smoothed many things. Anyway it's not something welcomed by the helpdesk side. If a client with IPv6 calls with problems, the've found out that most of the times the only way to not spend lot of time with the customer is change the setup to a ppoe v4 and forget about it. And we've used competent people for this test, not you average joe with 2 prior weeks training in networking.
Helpdesk agents hate it, and the come up with very good reasons.
This is either factually incorrect, or else you're using a definition of "modern" that excludes a substantial portion of real world isps.