Pickpocket apprenticeships have fallen by the wayside, and the actual skills to be able to pull this off are no longer taught to young people.
The rise of cashless payment norms reduce the reward for a successful pickpocket: canceled credit cards won't do anything for anyone.
America is a violent place, and it's easier to steal with violence or the threat of violence.
Other types of sneaky nonviolent theft have arisen, and things like identity theft or hacking or other fraud is an alternative outlet for those who might want to non-violently steal someone else's money.
All this will likely happen in Europe, as well. Just maybe a slower transition in the pockets where cash is still common (tourist destinations with international travelers).