If you were genuinely looking for a serious answer....
Norway & Finland are two of the wealthiest countries in Europe, both have huge natural resource-based export economies and small populations, so little financial incentive for their young people to get involved in prostitution in the UK.
Check out this list of comparative prices for goods & services across Europe...
External Link/Members OnlyI bet you haven't met any (genuine) Swiss, Danish, Swedish or Luxemburger girls either. Whereas the usual suspects lower down the list are commonly found...Poland, Romania, Bulgaria, Lithuania, Latvia, Hungary, etc. It's worth their while coming to the UK because their home economies are weaker and have higher levels of youth unemployment.
Culturally too, Scandinavia has a liberal view of sexuality, but a high intolerance of prostitution...there's a reason the Punter Criminalisation legislation is called the 'Nordic model'