My Australian ISP (Internode, now iiNet) was one of the leading promoters of IPv6 and was one of the first to offer such connections, years ago. Many customers used IPv6 with no issues for several years. Then Netflix came to Australia. Netflix, in addition to some Australian digital TV channels and a few local mirrors is excluded from the ISP's broadband quotas. But it turns out, quota exclusion only works for IPv4. So people set their account back to a IPv4 connection.
Because of this, valuable momentum in IPv6 adoption has been lost.
"The Avis WIZARD decides if you get to drive a car. Your head won't touch the pillow of a Sheraton unless their computer says it's okay." -- Arthur Miller