Passenger Trains > Door openings on NEC Regionals

Having ridden several NEC Regionals from Berlin CT to DC and from Berlin to NYP I have several questions regarding door openings on this portion of the corridor at the high level platforms.

Between New Haven Union Station and NYP there are usually 3 stops...Bridgeport, Stamford and New Rochelle.  I think because of track work, Bridgeport is down to several doors...Stamford has all doors open, I think New Rochelle has al doors open, and NYP has all doors open.  South of NYP all doors open at Newark, Metropark, Trenton, Wilmington, 30th Street, Baltimore, BWI, New Carrolton and DC assuming you arrive on the upper level.

The question is north of New Haven.  Wallingford, Meriden, and Berlin are all high level stations that can accomodate 8- 9 car Regionals.  And yet when you detrain at one of those stations only the doors adfjacent to the cafe open.  So if you are in BC you have to schlepp your bags up several cars to detrain.  Not that big of a deal and the crew let's you know what doors will open.

But why can all doors open at stops south of New Haven,but not on the SPG line? Is it a crew issue, a security issue (Wallingford, Meriden, Berlin are all unstaffed) or somethong else.

Just curious.