gemini://thelambdalab.xyz/phlog/2024-06-16-cgNAT-blues.txt
Another problem is the exhaustion of the IPv4 space (therefore NAT shenanigans). Why IPv6 kinda sorta did not go anywhere in some places, probably mostly those that have "large enough" IPv4 allocations has various aspects, some of which are detailed below. This is for America; other nations with large IPv4 allocations may differ in detail.
Folks stick with the same router for years (it works good enough, but does not support IPv6), and the local ISP monopoly isn't in a hurry to upgrade to newer routers and other supporting gear. Why would they take a haircut on their profits? Any competition would be most unwelcome: race to the bottom, a need to actually benefit the customer, etc. Cooperatives granted federal money was one way rural America (the other 80% of the country) got electrified back in the 1930s, so one might expect the lawful evil ISP of today to either lawsuit or lobby against such, if they've learned anything at all from history. Lacking a Franklin D. Roosevelt and following Citizens United, alternatives to the local ISP monopoly may be limited if you lack buckets of mammon to throw around.
There are mesh networks and such, but those may lack a clear goal, and you may need at least some centralization so that bad network activity (spam, botnets, etc) can be better managed, unless you hate the reputation of your allocation and never want to run a SMTP server there. What a cooperative or competitor ISP can actually do will vary greatly by location, resources, and the people available. Another approach is to double up on someone else's network connection to the local monopoly, which at least will dilute bill a bit.
I rolled out IPv6 for a department at a university and it was pretty terrible. This was somewhere in the 2010s, for reference. One problem was that various sites broke because their IPv6 was broken, so operating systems on my networks would pick IPv6 by default, fail some download, users would complain to me, I'd complain to the broken site, and usually after a bunch of emails going around the site would remove support for IPv6. One could set IPv4 to be the default, but that's hardly a good way to encourage a move to IPv6, and that's a hard setting to make on all the random systems users were dragging onto the network.
The campus ran a central network authentication service for web stuff. This service was not available over IPv6, so the recommendation was to proxy through IPv4, somehow. One way to discover this is by setting a host to be IPv6 only, and then see what breaks. Oh, you want DNS over IPv6?
There was a charming bug where Dell systems running Windows and an Intel network card would, sometimes, upon system sleep, start forging around 6,000 packets per second of IPv6 network traffic, and then you'd learn that someone had not put the uplink cable on the expected and documented port number and moreover had duct taped the cables into neat and tidy bundles that made it difficult to figure out which cable went to what offending host. There may need to be some amount of "keeping up appearances" for the rich investors who want to see only a neat and clean lab their money went to, so there can be tradeoffs here.
Somewhere down the line a remote site informed me that my networks did not support IPv6 (according, they had heard, from someone in the campus network group) so therefore it is quite impossible to support IPv6 network blocks for software licensing, and I was like, wtf?, because the campus network group had helped get IPv6 going. I had ticket numbers and correspondence and everything, but reality had apparently distorted in the meantime and now denied the existence of the IPv6 (probably, maybe, the core routers did IPv6 poorly and thus IPv6 was being put on the "nope" track until funding and support for better routers could be obtained? But hey give the football coach a few more millions, and groups can get silod so licensing folks may not know what networking had been up to years ago). Dealing with such takes time and generates stress when one could be doing more productive things, and always remember that IT is a cost center.
In theory if there had been leadership pushing for IPv6, and money, and resources, it might have gone better? Maybe the plutocrats need another Sputnik moment to light their car-wedged asses on fire, and thus get at least adequate amounts of blood to their brains, but it's hard to see from where or what that Sputnik might be. Basic network infrastructure probably isn't "sexy" enough, lacks adequate profit potential, etc.
Also, a few years (or decades?) spent fixing bugs and open sourcing and documenting everything from the hardware up instead of churning out new features might be nice, but that would cost money (and Capital would really not like that) and few vendors would want to reveal what a dumpster fire their ACPI implementation is. One can hope for but should not expect improvements here.