Most of my "Online" sources are a entry in the notes. I do NOT use many sources as they are not handled well by most programs.
If one was to follow the sourcing comments here and at other sites, there are a lot of issues, about them being used properly and are they really helpful to others.
A lot of online sources require a "subscription" so why list them?
The census images at Ancestry is NOT the source, but the ones that the government has. But the information needs to be listed in such a manner, that one can to go to ANY provider of the images and find the information.