In the US, Metro cargo flights only require 1 pilot. Are the regs different in the EU, or do the airlines choose to run 2 pilots?
There used to be exceptions that allowed single pilot commercial operation of part23 aircraft in Europe as well. But they require lots of recent hours on type that few pilots could meet.
More importantly, the duty and rest time regulations are very restrictive regarding single pilot operations. This makes night freight operations with one pilot almost impossible. When I flew express cargo (Metroliner and Cessna 404) we used to call the second pilot "duty time extender"...