I sat the other day in the Mainz-Kastel Bahnhof (train-station). To be honest, over the decades, it's more or less a urban-boarding point to get either to Wiesbaden or Frankfurt. The station itself doesn't exist....it's a Turkish pizzeria shop now.
If you sit there and admire the two platforms and three tracks that cross the old station....you tend to notice the security cameras.
All total? At least sixteen of them.
Twenty years ago, there might have been one or two max.
You see the same thing around the Wiesbaden station now....although probably triple the number of cameras. Frankfurt? I'll bet there's over 200 cameras around the station.
Is there some guy watching these? Probably not. It just goes into some digital database and sits there for a month, and then gets overwritten.
No one thinks much about these anymore. They just accept the fact that mass surveillance is a normal thing now and you have to play along with it.
One amusing added feature is the 'pointy-sticks' on the top....to prevent birds from landing and crapping over the camera.