And if I remember correctly, the vaults of the first two games had a heavy backup security door after the entrance corridor from the main vault door. Its use either being to keep those from attempting to exit, or another hindrance for those trying to enter. comparatively, the Capitol wasteland vaults have a rather overly large entrance area, with door that appear rather meager (Take a look at the security door opening in vault 13, its got several layers.) And in all likelihood if the overseer is watching as some big green mutants, or nee're do wells trying to drill a hole into the main door and pack it with explosives, the security force would raid their well stocked armory, and open fire as soon as the vault door was opened by the overseer, halting the attempts to drill into it. The entrance tunnels are only so large, those not crushed by the door (In the case of those vaults on the west coast.) Would have nowhere to flee from the security forces fire (With the well stocked armory all vaults were supposed to have, Just like how the geck was supposed to be standard equipment for a vault.)
Though I think if the vaults location was well known (Every god damned person knew where I came from in Fallout 3), that door would have been gone within the first few years from the desperate attempts of the survivors thinking that the inside of a now doorless vault would provide safety. Vault 13 was only safe because it was a bitch to find. Aradesh looked for it for the rest of his natural life, knowing its general location, and yet he could not find it. Telling the caravans where it was, that just created new problems in the form of it being a big frigen sign post.
As far as the cannon and the internal realities are, the main reason for vaults survival or lack thereof was how well hidden their locations were. It seems as though the ones hidden beneath major cities were discovered, or well known about. Or their experiment was of a relatively short duration. As well, the immensely close proximity for the vaults in the capitol wasteland was very odd. It would seem pertinent to keep them well spread out, especially one that were well known about. IMO if I know the general locations of six or so vaults in close proximity to each other, in the capitol, which means a good chance of politicians being in them, while being a military leader in the red menace, I would make sure to bomb the hell out of dc just that little bit more. IE giant crater.
And no-one mentioned how the headquarters for Vault-tec were supposed to be in LA near the prototype vault (With the outward opening vault door) while appearing in washington DC looking rather unlike the vault-tec headquarters we knew and loved (A massive, dominating structure of immense size and wealth.)
