Lower-case was not common on printers and terminals in the 1950s and 1960s (and into the 1970s).
612 karma · joined July 24, 2008
(Author of _Annals_ paper here.)
https://www.amazon.com/exec/obidos/ASIN/0804738718/ref=nosim...
Actually it only took Peter Landin a few years. For example see:
P. J. Landin, The Mechanical Evaluation of Expressions, The Computer Journal, Volume 6, Issue 4, January 1964, Pages 308–320, https://doi.org/10.1093/comjnl/6.4.308