[...] a public institution is really not a great example of the general population [...]
Which I touched upon in my disclaimer, but in some ways it is a great example. Public institutions are defined by the general population, indirectly through their representatives creating the rules that govern them, and directly through contact with the public at large. Now if all our institutions still use this very outdated technology, and you can have trouble convincing them - during a global pandemic mind you - that using email is just as safe as using fax (so not safe at all basically), then that speaks to a larger mindset in the general population.
Many in the general public are also a lot quicker, some might even say careless, with adopting new technology of course. But as a society we are rather slow, and there are surprisingly many individuals who are hesitant or entirely resistant to adopting new technology. The fediverse usage is a bubble in a bubble here.
The internet infrastructure is another good example for this on the societal level, as there were plans in the 1980ies [!] to lay out a glass fibre network between every publicly used building in the country, which would have gotten us a good part of the way towards adopting this new material at scale. But in the end it was deemed unnecessary and too expensive and the project got canned (mixed in with rumours of "close friendship" between the chancellor and a major copper producer). Instead now we have people running around thirty years later and collecting signatures at the door for last-mile fibre network projects that seldom make quorum and thus almost never materialise public funding.
I'll have you know that this is famous sci-fi author Charles David George Stross posting an excerpt from his seminal novel Don't Create The Torment Nexus. The warning is right in the title, I'm sure nobody will be dumb enough to ignore it!