There was a great sign at Wat Pho in Bangkok last week:
There are gangs, but don’t go assuming that because you are in Thailand that they are Thai.
So if the person with their hand in your pocket is Thai, they are not stealing from you. Unfortunately the sign is incomplete, so we don’t know what nationality the pickpockets are. But if the authorities are sufficiently aware as to be able to erect a sign in warning, surely they could identify the non-Thais from the outset and prevent pickpocketing altogether?