It's "national service". A concept perhaps alien in the US, but basically most countries have a programme where eighteen-yr olds have to go through service in a government job, either in the army, police, fire or EMT. I mentioned that as the comment above mentioned the IDF.

Police standing around in subways is still a deterrent from bad behavior, especially when coupled with a justice system that doesn't reward criminals. See Japan, Korea, Singapore, Dubai, Israel, etc.