They are all free text articles written by humans. Doesn't look like they are generated from some structured dataset. Can't tell if there is any web content management system behind it.
But in any case, you are right to serve static contents using a dynamic engine is not the best way, since it will incur penalty by fighting the same processing power within the same engine when other parts of the site really requires the dynamic behaviour.
In general cases, there is not much penalty beyond the first load since caching at various levels may just shortcut the access.
1) Browser Caching due to expiry headers, using modified/expiry date time, ETag
2) Caching at CDN level, cache proxy, if it exists
3) Caching at App Engine level, depending on how the static html is served, server side includes, template includes.
4) File buffer
Less of just branding some of these developers or administrators as inexperience, sometimes I guess they just do it out of conformance, so everything just get served under a certain URL pattern, which there could be systems or layers on top of it that detect based on the URL pattern and apply protection or authorisation. They might want to just map against "http:\/\/.*\.aspx" instead of also including the "html" portion for simplicity.