Could anyone (non-military) in the present day "exceed mach 1 over a regulated area"?
Yes, In the U.S.A there are many privately owned ex-military jet fighters that are capable of exceeding Mach 1. It is quite conceivable that a privately owned fighter jet has exceeded Mach 1 but not reported it or been caught by the authorities.

You can search the FAA civil registry by type:  FAA REGISTRY
Make / Model Inquiry

Here is just a partial list of privately owned supersonic jet fighters in the United States:  



Lockheed F-104 
McDonnell F-4 
NORTHROP F-5
MIKOYAN-GUREVICH MIG-21 
MIKOYAN-GUREVICH MIG-23
MIKOYAN-GUREVICH MIG-29
Sukhoi SU-27


These two aircraft are owned by the Collings Foundation in Florida and are available for airshow demonstrations.