The trafficking is surely universal in Western Europe. For example ,the police in Nice discovered that nearly all the 'girls' they found were from Eastern Europe, commonly from Albania.Only the 'high class' workers were French, and even those were suffering competition from Russians.When we have had raids in Cambridge, the story has been similar; the girls were Eastern European, in the main.
Our law on prostitution is a mess. One girl working alone in premises commits no offence, so it would be odd to prosecute and punish her clients! If she solicits in the street, she commits an offence and so do the men who approach her for sex or who are cruising around for that purpose. We prosecute people for leaving prostitutes' cards in phone boxes but not newspapers who advertise 'personal services' of 'massage'. It's all a little odd.