Except with cp , -R is the safe one and -r is the dangerous one. And there are tons of little inconsistencies like this.
As a former sys admin, I did that all the time. Who the hell can remember how to convert an SSL certificate to load it into a Glassfish app server? Didn't mean I couldn't step through all commands and figure out why it did that before I loaded the new cert... And next time, I just need to go to my quick hack repo for the magic incantation.
On a Unix based system, tar is just used so frequently and for so many purposes, that not understanding it feels a bit like working in a shop and not knowing how to use a roll of tape.
(I'm a developer.)
Sequences of commands sometimes get pasted into a conveniently-located text file; if I find myself repeating the operation I might turn it into a script, a shell function for my .zshrc, or an alias.
Just 10 minutes ago: mysqldump [args] | nc -v w.x.y.z 1234 nc -v -l 1234 | pv | mysql [args] (after an initial test that showed adding "gzip -1" was slower than uncompressed gigabit ethernet.)
Part of the problem is that each command line utility has its own flag language, and equivalent functions often have different letters. For instance, very often one command has "recursive" as "-r" while another has it as "-R". It's impossible to remember it all unless you're a sysadmin.