Prostitution Suddenly Immoral With Fixed Rate Pricing

I will try to be somewhat delicate with this topic.

Prostitution is legal in Germany. The current economic environment has affected everyone and in German brothels business is down 30%. To combat this, some brothels have turned to fixed rate offers modeled after "all you can eat" buffets (no, I'm not making this up. You can read the story here.) For one price, you get all the working girls you can handle.

This has set off a firestorm of controversy over the innovative promotional tactic. In a country where prostitution is legal and well tolerated, "flat-rate sex is an immoral development which cannot be tolerated."

Without taking sides on the issue of prostitution, I see this argument as absurd. You can buy-one-get-one and that's OK, but buy-one-get-more-than-one suddenly becomes immoral???

I can't wait to see the religious justification for this argument. What do you think?