Except styles that makes no logical sense.
To save a mere 122 thousand people the government would have to spend the same as four and a half years worth of the real us governments income in 2010. Surely it would have cost less, and saved more, to build a massive house style anti missle system. The real world population of Vegas is 2 million. House did a better job at saving people at a much lower cost (as he financed it himself and I'm not aware of that many folks who can come up with 9 trillion).
The country is supposed to be gearing for an inevitable war (or fighting it) at the same time.
Project safehouse only makes sense if there's something else going on.
You are not thinking like a politician.
The World is falling apart every nation is at one anothers throats. Nuclear war is a very real threat! You people turn to you (the governmnet) and say "What are you doing to save us!"
So you come up with "Project Safehouse" a large showy project to calm the people into thinking you are doing something to save them. Much like "duck and cover," which in truth, was stick your head between your legs and kiss your butt goodbye. Some Vaults could save more the just 1000 people but you are right there is no way 122 Vaults could save 400 million. There were never meant to save that many. Just enough to keep America going but the main reason is to show the people "Hey we are doing something."
Enclave having ther own goals usurp the project for their own goals. They have to make it look like they were saving people. Really do you think the American government went around saying "Take shelter in our vaults that will most likely kill you?! And by the way we spent 9 trillion doing it"
In a Nuclear War the only real way to "win" is to be the last man standing. 122,000 may not be alot when you think 400 million but its better then Zero. Sure there would be people that survive without being in a Vault but the Vaults were built to show the people that "Something is being done." Also when the world is going to hell, you'll just end up printing money. Much like is happeneing now. The Vaults started being built in the 2050s I believe.
Which would also expalin Vault Zero. The Vaults would need to have a Hub, a place where all the Vaults can be linked which would help rebuild. Enclave not caring about saving people made the cut backs to Vault Zero which caused it to fail. Which killed many governement people not apart of the Enclave.