Those case differences have meaning, -r is generally not dangerous while -R is; it's capitalized to make you stop and say hmmm, should I do this. All commands have the same flag language, command -options, and are all easily documented by man command; it quite literally couldn't get any simpler and unnecessary to memorize since you can look up any flag on any command with the same man command. Those who find it confusing haven't spent the least bit of effort actually trying because it's actually very simple and extremely consistent.