This is actually the only thing in ESB that bothers me. There is no way a electronic item like r2 would survive the swampy beating he takes on dagobah. When he fell into the swamp, he shoulda died realistically.
With the advent of phones that are water resistant enough to take a dip and keep working, not to mention the electronic items that construction and repair crews use on a daily basis, even in wet weather, I don’t see what the problem is. R2’s sensitive electronic components are protected from the elements and the rest of him can endure all sorts of conditions. Makes complete sense.