Sure, biggest Brand/Monopoly (and largely US) Tech is of course an interesting situation with a few different directions for interpretation. Yet, I think that many of them simply have to add DNSSEC, IPv6, etc as soon as the numbers finally look too much like 50%+, I.e. MS is about half the sites and already has selectively added it, usually where the consumer brand consequence is theirs via a SaaS product.
Secure shell had to wait quite a while for gradual adoption by anyone new and caskets of the older to pile up. SSL wasn't exactly shiny new in 2014 when LetsEncrypt was brought in to make it prevalent together with Google pressure. Similar pressure has the same groups picking DNSSEC experience up just in the last year.
If we put aside the advertising for a moment, the US had the same problems with every technology that is newer than landlines. Big investments in companies that will be prevented from failing will try to keep the US behind the trend but a few US companies will see that they better get ahead of where the rest of the world is going with or without US tech.
No, it didn't. SSH adoption was nearly universal with a year or two of its release. TLS was nearly universal on commercial sites long, long before LetsEncrypt. SSH and TLS are not comparable in adoption to DNSSEC.