To maintain a police state you need mass surveillance and informants. Secret police make you disappear long before your armed rebellion starts and your neighbors will be too scared to get involved or are the informants who turned you in. Flooding the streets with police isn't needed, along with informants they can always work with gangs like Assad does to act as street enforcement. The state's only cost is looking the other way while trafficking goes on and paying a network of snitches in every community.