Hi Yaroslav, the problem we face here is that there are no technical means to use this scheme.
Firstly, there is only one UploadCampaign for the US (same for Canada, the Netherlands, and Russia) - and secondly, the current CentralNotice and GeoNotice systems do not (truly) enable us to set up different campaigns for respective administrative divisions of a country (in this case, mainly the US and Canada).
And just like you wrote, it would be a nightmare to track post-deadlines pictures: how would you tell if a user uploaded a picture from California or from New York? What would matter: the location of the object (based on geo-coordinates and GPS data, for example) or the real-life location of the user at the time of upload? ;-))
I believe that besides the countries you mentioned - Canada, France, the Netherlands, Russia and the US - also Mexico uses different time zones. (Any countries I missed?) I would love to hear from people from those countries what they think as to what should be done here.