It's all about "Crime Clear-up" figures. Everyone caught in your village counts against a little old lady being mugged for her pension by three shaven headed louts in Skallypool.
One DD conviction = one crime solved without danger to the two officers concerned. Putting in the effort to be "on the streets" preventing muggings etc is hard work. It's a no-brainer to their target driven culture.
What really p*sses me off is when sanctimonious twats get on the box spouting drivel about "A crime is a crime and we treat them all equally" ~ do they bollox!