It sounds like the 2005 models had some exemption notice on the door. My 2009 Elise says "this meets all the legal requirements...".
Up here in Ontario we need a front plate. What bothers me is that between our 10 provinces and 3 territories, only 4 of 13 require that. It seems that one could argue that if the majority don't require a front plate that the other regions should drop that requirement.
Anyways I have been pulled over a few times and depending on the cop you can get a warning or a ticket. I've been able to go to court for each ticket and promise to add the plate. In each case the ticket was dismissed.
Bummer. The exemption IIRC was for 2 years. So all cars MY08 and newer would not be exempt.