Max and maximum: why the difference?

This would be really confusing. It’s better to just use two functions rather than trying to guess what should the function do. See Merging `max` and `maximum` · Issue #11872 · JuliaLang/julia · GitHub

The deprecated behavior has been, well, deprecated so it’s irrelevant now.

It’s not inconsistent. The “inconsistency” is that some types are comparable and some are not.