I mostly use my left hand I guess to thumb up. But your post is interesting, it would make sense to me to use a right-hand thumb up by default since right-hand

I mostly use my left hand I guess to thumb up. But your post is interesting, it would make sense to me to use a right-hand thumb up by default since right-handed people are close to 90% of the world wide population. It would be interesting to know why some companies just went with the left-handed version, if it's an aesthetic choice or just coincidence.