Maybe we are talking past each other, but I am not so sure you “see” the causation the way it probably is (I am reluctant to call myself an authority even after nearly a decade living in Japan, so take my perspectives with a grain of salt). “Western” societies apply corrections the way you seem to ascribe them to Japan: A strong arm and stern reminder. In Japan, it is instead “soft” and more akin to the stern look your mother gave you back in the day. Begging is not something that happens, not because it is immediately clamped down upon, but because it does not happen in the first place because of “collective social restraint”.
In another comment you wrote: “I don't even want to know my neighbors exist”. Since Japan is a more collectivist society, you will be acutely aware that your neighbours exist at all times. Heck, not only your neighbours, but every individual around you at work, in public, etc. and constantly be reminded by your fellow Japanese that you better “behave” and conform according to the perceived norms or get glared at disapprovingly or – worse – even ostracised. At least to my eyes, this is where you find the source of the societal phenomena you seek – not the police or another central authority.