Local law enforcement helicopters are the   

You have to remember how it all started.  Lots of military surplus aircraft back in the 60s and 70s, LE and FD began to acquire them basically free, and created aviation units to help with the ground units.  Over time, aircraft became obsolete, parts hard to come by, but air units had become established and popular so they continued with used and sometimes new airframes.  If a police or fire department didn’t have a helicopter it was behind times.  If a hospital didn’t have a helipad to receive or send patients by air, they were 2nd rate.  Sure, todays technology with drones in many cases could replace expensive helicopters, but it’s difficult to let go