The reason that this has caused so much alarm is purely scientific and not particularly because of the potential danger, I think.
Doctors and scientist have been surprised to find - for the first time in decades - a WILD polio virus emerging in the Western hemisphere. It was thought to be totally eradicated, hence the surprise (and alarm).
Health authorities have taken this as a warning that vaccination programmes must be carried out - like they are in almost all Western countries - or the goal of totally eliminating polio will not be reached.
So, I doubt there is a conspiracy or anything remotely like it. Just a genuine surprise - which will always cause the media to become interested, whereas hep. A is so dreadfully common (unfortunately) that it is hardly ever mentioned.
Regards,
Susanne