1) THE COPS LOVE THE OVERTIME! WORKING 12 HOURS SHIFTS ON TIME AND A HALF FOR RELATIVELY EASY STANDING AROUND WORK IS A STEAL.
2) LOCAL GOVERNMENTS OF THE BIG CITIES ARE USUALLY SYMPATHETIC TOWARDS THE PROTESTORS.
3) DUE TO ALREADY HIGH COSTS (see #1) LOCAL GOVERNMENTS ARE LOATHE TO SEND ANYONE TO JAIL AND ENSURE EVEN MORE $$$ DOWN THE TUBES.
True. The most virulent demonstrations have taken place in those cities, such as San Francisco, Chicago, Philadelphia, etc., where the city councils have passed antiwar resolutions. In the three cities I have mentioned above, the governors of the respective states are Democrats and are unlikely to override the lenient treatment afforded by liberal Democrat-run city governments by sending in state troopers or the National Guard. Short of a declaration of war, which has not been made, the Feds can't send in troops or Federal law enforcement officers and arrest the antiwar vermin on sedition charges.
It may be that the true Americans of such cities have no alternative but to deal with these drug-addled, brain dead scum if the local authorities won't do so.