Not just governments. I can get in my car and go to the three main shopping malls in my relatively large Portuguese city. I will very easily MITM a bunch of people there, no problem, using a variety of attacks. They won't realize that I'm now sucking all their traffic in and modifying it as I please.
After I've done that, if they visit any HTTP link, I can inject whatever I want there: crypto mining, download links to a modified/hacked version of their browser, social engineering attacks (phishing), cookie hijacking, etc. Notice how I can modify whatever HTTP page you have to link to websites you think are secure (banks, social media, websites), but that are modified (e.g. via sslstrip, or just by being similar-but-not-quite-the-same-hosts, etc)
Many months ago I went through this here: https://news.ycombinator.com/item?id=25123366
It should be a duty for all sysadmins to make sure their sites are HTTPS. Sure, if they're only in an intranet, HTTPS is likely overkill. But any publicly hosted website should be forced to be HTTPS.
One single HTTP website leaves a person vulnerable to millions of attacks. Many of these are still present on the web with HTTPS -- but at least then they'll typically be done by the people running the HTTPS site, not by someone in the middle.
For those sites you mention, confidentiality and availability will not really be impacted by HTTPS.
But the integrity can be.
Case in point: See this comment https://news.ycombinator.com/item?id=27507826
To be clear, I'm very pro-SSL and have used LetsEncrypt for years on all my domains. I was just taking issue with the notion that someone's web server serving static content could be breached just because it didn't have an SSL cert.
Because unencrypted HTTP allows attackers to MITM the traffic, they can do things like put ads on your site, inject malware or bitcoin miners, or just replace your site completely. None of those affect you, the site owner, directly, but ìt subverts the purpose of your site and lowers the value and trustworthiness of your site to your visitors.
It’s a necessary level of defense but it is NOT sufficient- especially if you never check certificates.
SSL doesn't magically secure your servers, especially not if all you are doing is serving static HTML content and images.
All HTTPS really does is encrypt the HTTP traffic while it is in transit. The main reason this is important is because someone monitoring network traffic (for example, at the network switch) could theoretically see raw passwords and stuff being sent over the wire in plain text.
If your web site doesn't do anything with user names and passwords or form fields that accept some type of text that needs to be secured, then HTTPS isn't really doing jack shit for you (other than making visitors "feel" secure).
Edit: I forgot about man in the middle attacks from internet providers and governments who might modify the HTML and image payloads being transmitted to the end user. I guess HTTPS would be useful for prevent those types of exploits on static sites. So that pretty much means HTTPS should be on every site, if for no other reason than that.