It’s not a scam, unfortunately.
I have been through the same mess recently, and what it boils down to is a fine for driving in the restricted zone in central Florence.
Tourists are permitted to drive in the zone, but only for the purposes of accessing their hotel, and subject to applying for the permit in advance (which no-one does).
You can log onto that dodgy-looking website and access the details of the infringement, and can even download the photograph of you in the car in the zone!
The way to resolve the issue and avoid the fine is to ask your hotel to fax confirmation to the agency that you were staying there – note only certain hotels are applicable given they need to be in the restricted area.
The one charge I was unable to avoid was that from the car hire company for processing the paperwork – which is probably fair enough, although they might have warned customers in advance re notification if they weren’t making money out of it.
Incidentally, the only reason I bothered with the above was a return trip and the risk of being flagged at the airport!
P.