You made two claims of fact about the disappearance of manual office typewriters. The two claims were inconsistent with the facts as I recollect from my own experience so I did some research which quickly came to show actual facts to be contrary to the two facts about MANUAL typewriters you stated.
That has nothing whatsoever to do with manufacturing ~ just availability and general usage levels.
We are talking primarily about a government office in Hawaii just 2 years after statehood. No doubt they got some handmedowns from the territorial government, and no doubt the territorial government before them got handmedowns from the Department of Navy.
My personal knowledge regarding Navy is that their headquarters offices in DC at least as early as 1942 had electric typewriters throughout. Young ladies who had training or experience with electric typewriters had an edge in the typing test using electrics.
Department of Army might have been scratching characters on wooden spoons for all I know of what they were up to, but the Army Air Corps also had electric typewriters ~ even in the hangers at Bolling AFB.
There were some manuals around but most of the build up for the war that took place around here was "new" with "new stuff" and even "new buildings" (SEE: Pentagon), and plenty of rehabs for the older barracks type buildings that were finally disposed of by Richard Nixon.
I have no doubt there were hunting lodges in the Rockies without electricity and they might have had manual typewriters ~
What you must try to do is keep in mind that just about every issue has been discussed earlier with all appropriate caveats and conditions established.
Now what is it exactly you were so concerned about regarding typewriters ~ regarding electric versus manual, and manual versus electric.