Which pngcrush?
No idea about pngquant except if you have an ancient version you should have that option. Or maybe 2 installed versions and it's picking the wrong binary. Oh well, not a linux forums here, that could quickly become boring, sorry.
I certainly can't speak for others, but I find your “boring” interesting! I've always been impressed (and maybe a little jealous) of you folks who could have such confidence in the command line, and all the power that brings.