Don't know why the police were involved. Some people (e.g. Max Mosley) pay money to get a good hiding as part of a sex session.
Sure, it's just like owning a yacht. Half the people doing it are paying to do it and the other half are being paid. If they could all get their acts together everyone would have fun and it wouldn't cost a bean (except for wear and tear on whips, handcuff maintenance, hire of concentration camp uniforms etc).
(I know, I know, strange things to find on a yacht).