“Cold on the right; hot on the left” is a jab that is not particularly endearing to plumbing engineers. If it were ever uttered, it’s usually in the context that the task at hand is very easy. I will be the first to admit that the phrase stresses me out sometimes, lest I forget it. I always like to add “don’t forget waste down and stink up!”
From what I have seen in the field of engineering, what is easy is letting things get complicated. We seem to be pretty good at making things complicated; just get a few of us in the room together and watch what happens. I would consider details like faucet orientation as simple, something different than easy, and simplicity requires effort.