It is time that you American and British idiots looked at a map and realized that winters in Russia are a lot colder than in Britain and the US. Perhaps you should recall your last winter in the UK/US and giggle at how the temperature dropping just slightly below zero would wreak havoc, and a couple of snowflakes that managed not to melt would paralyze your countries for days. Then try and grasp that in Russia twenty and thirty degrees below zero are the norm in winter, and they naturally do everything to conserve the warmth of their homes. Which includes double doors at the building entrances -- yes, with unheated space between them, because one must truly be an idiot to maintain tens of degrees of thermal difference in a place that has almost unobstructed heat exchange with the atmosphere. That often includes double doors between the stairway in a подъезд/парадная and a flat because there are still tens of degrees of difference between a flat and the stairway.

Yes there are double doors but they do not have to be steel doors. Speaking of which, you really ought to dissect an average "Western" door for your education, I bet you're going to be surprised upon finding steel inside one. Does that mean anything about the paranoia of its owner? Probably it does, but not more than it means about the resistance of the door to fire.

But, of course, in Russia steel doors only signify the wickedness of the Russian mind.