Thanks to @Viveka_CD @barthbradley @RobDraw for replies.
To clarify, my Revit 2019 was installed by the "Autodesk Desktop App" that sits in my Windows 10 System Tray and prompts me for updates. The installation is to a single, stand-alone computer, that is not part of a network deployment. I do not recall that the installation offered me any choices about where to install content, but if it did I would have accepted the defaults.
The content, including the "Family Templates", "IES", "Libraries", "Lookup Tables", and "Templates" folders were installed under the folder "C:\ProgramData\Autodesk" rather than the normal "C:\ProgramData\Autodesk\RVT 2019". (Note that the "ContentPacks", "Recent", and "UserDataCache" folders were installed in the normal location.)
In my researching this issue on the forums and speaking to colleagues I have seen that others have had the same experience.
My comments on these forums have elicited some responses that seem odd to me. I will admit to being kind of “old school” (after 30 years of implementing Autodesk products) but I think:
1. Autodesk should care that it’s installation program is not working properly. It is helpful if we users report our experience back to them so that they have an opportunity to correct the problem.
2. It is generally not advisable to move folders, or change paths, from an installation manually. These things should be done by the installation program.
3. Leaving the content in a non-standard location will ultimately be problematic. For example, the "C:\ProgramData\Autodesk” location does not properly distinguish between Revit versions.
I've already reported in a longer post to the Installation Forum about my findings with correcting the problem manually. I've also been advised to redo the installation (or at least the content portion.) So, for my purposes I can let this topic go, but I don't really see it as "solved".