The place I work has https-everywhere as a policy. We had to fire a vendor called HubSpot in part to maintain that policy. HubSpot's service uses a subdomain of each customer's domain to provide their service, something like "info.example.com".
And they also use a content distribution network. They will deploy an https certificate across that CDN, but they charge US$600 a month for that service. Because we didn't want to pay that fee, we couldn't use https on the subdomain dedicated to HubSpot work.
I suppose web properties distributed by some global CDNs are stuck on http for that reason.