So just installed the PNW loam dropper on the Ripley and it has about 1-2mm lateral, ie, side to side play. The KSLev had the same and I seem to remember my fox transfer on another bike had the same.
Is this just a ‘feature’ of droppers ?
Yes, in use you wont feel it. If they had no play the friction would stop them dropping easily.
Yes, but it varies across brands and models.
My Anthem came with the older version of the Giant Contact SL dropper which had tons of lateral play (3 or 4 mm) from new. Warrantied by the shop I bought it from but the replacement wasn't much better. When I serviced it I saw that some of the parts in the sliding mechanism were plastic.
My current Brand X dropper has barely any play (1mm or less) but it is there. Not noticeable at all when riding (whereas the Giant was a bit rattly but not unbearable). The sliders inside the Brand X are brass and seem to have much tighter tolerances than the Giant.