USA arcade operators constantly pushing for games that will bring more profits combined with the language barrier probably made the Japan developers reach for the simplest solution, I guess. Easiest way to bring more quarters was to suck them. There have been cases where some Japan versions of games were harder but none come to mind. Japanese people have historically been good at mastering games. IIRC the first to find ways to live forever on 1 quarter in Gauntlet for example were Japanese folks. If there is some glitch to exploit they find it.