>>3401503Average height of men is around 175cm
Average weight is around 80kg
Which puts the average suit size at 40R, assuming an average build.
Clothiers are for profit, and are able to maximise their profits by appealing to the biggest market.
A 34R is so vastly different, if the jackets are machine made I wouldn't be surprised if they required narrower/extra machinery than your standard 38/40/42.
You are wonderfully ignorant if you weren't asking that rhetorically.