Most police bikes I see in the US are Harleys, I don't think they're buying anything out of practicality. If they were, you'd see a lot more BMW police motorcycles.
Michigan State Police somewhat controversially switched to BMW motorcycles in 2012, and actually disbanded the motorcycle unit for awhile because of safety issues. Apparently it's returning this year, still using the BMWs.
BMW models with direct shaft drive and horizontally opposed twin pots are better for safety in several ways.
Lower centre of gravity, some "extra" leg protection in sideswipes | converging hits on roundabouts (from the pots and pot crash bar protectors), and zero chance of chain wear with better direct power pickup | engine braking from the shaft.
These are all grounds for some heated debate wherever two wheels gather, but I'll swear by them.
