Commands aren't case sensitive. Just try it! Tab completion even works if you start the command lowercase.

As for needing to know aliases... Did the knowledge that 'du' stands for 'disk usage' exist in your brain at birth, or did you have to learn it somehow? That criticism is nonsense.

At least with powershell, commands have a canonical, explicit name with standard verbs and nouns; and a short alias that's equivalent to the initial command in every way. What I also like is that parameters have aliases too: you can write - WhatIf or -wi and it'll work the same. And everything is documented.