But it's true -- the public CV page is free.
The private CV page that employers see through their private search interface is not the same as the public CV page (it has more information and other features) -- and that is not free, nor is it tagged as such.
Remember, you pay a nominal yearly fee to file your CV which makes your CV visible in the private CV search engine. This doesn't have much to do with the public CV except that some of the information on the CV is similar, depending on what sections of the CV you've marked as public-visible.
To clarify: we can't have any indication on the free public CVs that the user has paid to file, and be listed for private employer search. Doing so would "out" anyone that has a public CV and happens to be looking for work. Their current employers would be able to tell (by the absence of the "free public CV" tag) that they are not happy with their current job and seeking other employment.
The free public CVs and paid private employer search are two different worlds, and bridging them in the manner you are describing would destroy both.
I am sorry, but if this is a problem for anyone, please email email@example.com and we'll be more than happy to refund your money in full.