I think it is just a matter of which presentations you remember the best. In the video below, there are a couple of places where it is all caps. I'm not sure I recall anything not in all caps on a Commodore 64. Not that I spent much time on one, but it was pretty much my only exposure to Logo.
https://youtu.be/Nv5jl1l909s?t=366
https://youtu.be/Nv5jl1l909s?t=402