All UPPERCASE is easy: it was used for emphasis in written English from before computers. I'm old enough to remember platforms that had no lowercase -- Univac 1108s, for example, used a 6-bit character set and had no lowercase letters -- but those systems predated email, and weren't used for actually communicating with people except in very constrained ways. BTW, Swiss bankers don't use Helvitica. They use Fraktur.
Information about American English usage here and here. Floating point issues? Please read this before posting. — emc