Today I recalled that as a student in the 70s I discovered that the line printer attached to the Univac 1108 mainframe at my university's computer centre could print lower case characters. So I modified the Ratfor workalike of the Unix roff program that I had entered into the computer to treat all alphabetic characters as lower case, and implemented escape codes to raise (and lower later) the case for capitalised words and acronyms. This was to be able to use punch cards as input, as the terminals were not always available. I don't remember if I implemented auto-detection of beginning of sentences, probably not. I even typeset my undergraduate thesis this way.
At that time I was using Ratfor as a structured Fortran, having been introduced to it and the book that described it, Software Tools, at a work experience stint, and had not yet encountered Unix in person. It was only when I did my masters that I learnt Unix and C.
I have wondered if the computer operators were surprised by the appearence of lower case printout since everybody else seemed to accept that UPPER CASE was the only case available.