I'd estimate about 75% of the time I'm on an HTTPS website.
> The BBC has used HTTPS on pages with forms that submit secure data, as has been the historic standard.
This is insecure as the HTTP page can redirect to a malicious HTTPS page from a different domain.
https://www.google.com/transparencyreport/https/grid/
For example, the following are all in the world's top 100 websites and none of them support any form of HTTPS. The link includes quite a few more.
* alibaba.com
* ask.com
* ask.fm
* baidu.com
* cnet.com
* cnn.com
* dailymail.co.uk
* ebay.com
* globo.com
* go.com
* goal.com
* goo.ne.jp
* imdb.com
* live.com
* mirror.co.uk
* naver.jp
* nytimes.com
* onet.pl
* pornhub.com
* telegraph.co.uk
* uol.com.br
* weibo.com
* wikia.com
* wikihow.com
* wp.pl
* yahoo.co.jp
* yelp.com
* youporn.com
New York Times still dosent have HTTPs.
Instead, the burdens are on testing and developing the migration. For example, they'd have to inventory and edit everywhere they use http:// (hardcoding the scheme in your front-end code) instead of //. Furthermore they have to support third-party ad networks deliver active scripts (like javascript) over HTTP. Having HTTP while on HTTPS will create mixed content warning and for active contents browsers will block these violations immediately, thus breaking the website.
To me, the decision of not migrating to HTTPS because of infrastructure capacity is always a myth. Someone has to prove that with data.
It hasn't been "standard on full sites for years", and still isn't now. Only recently with the 'HTTPS everywhere' move has the idea that public sites with no authentication should support HTTPS. And even now, that's not a universally supported opinion, because of its effect on caching.
The BBC has used HTTPS on pages with forms that submit secure data, as has been the historic standard.
Moving a site as massive as the BBC, which spans multiple domains and subdomains and has millions of pages is a big task. Note how you can still see news articles from the late 90s at the same URL. So, yeah, I can understand why writing a blog post about it is worthwhile.