Yet the four largest cable networks and all of the mobile networks in the US have had full IPv6 support for years as do AWS, Google, Azure, Digital Ocean, Linode, and many other hosting providers.
Could you explain what "most" means where you are?
a vast number of large non-us mobile networks and non-us fixed eyeball networks use cgn, sad to say. as saku says, when v6 was 'designed', the expected transition time was relatively short. yes, they had negative ops clue; in fact, ops were openly declared to be the enemy of the v6 'architects' (remember NLA and TLA). this led, among other things, to the short-sighted plan for dual stack to be the only needed transition mechanism. the first problem with this is that it requires as much v4 space as v6 space, oops. thus was born the plethora of transition mechanisms. imiho, v6 will continue to slowly deploy with some lulls and some spurts. and mailing list religious rants about it will continue unabated. in parallel, efforts to de-frag the v4 space are worthwhile, though they will only slightly alleviate the v4 shortage. we do what we can. i only wish we would make less ineffective noise about it. randy