dfk41 Well, I have no idea what is “traditional”, but based on ~40 old machines in the ECM museum (from @DavecUK ’s video in April), there is a slight prevalence of steam wand being on the right - however plenty of ‘left handers’ from the 1950s and ’60s.
Many 2-group machines seem to have two identical wands on both sides (no “water” wand - which would make sense, considering that 1) tea/herbal infusions were not that popular in Italy, and 2) electricity was bloody expensive, so you’d heat water up on a gas/coal stove - keep the electricity for the premium brew!).
Also, ergonomically, 90% of people are right-handers, and it’s easier to make the fine movements by holding the milk jug with your right-hand wrist and use the left hand just to feel temperature if the wand is on the right - or at least that’s what I find as a cursing left-hander.