Look at the time, money and effort that has been going on for a decade plus of geo-engineering (chemtrailing) Worldwide IN BROAD DAYLIGHT with hundreds, thousands of these aircraft and all the airfields and associated ground support ON A DAILY BASIS, yet not a peep from any quarter. I've even given up asking folks if they have noticed this obviously strange and unnatural activity in the sky as to a person, they haven't.
So any argument that such a large scale project as connected underground cities complete with maglev connecting rail would not have gone unnoticed, is complete rubbish. Just look up at the formerly blue sky for Exhibit A, and only exhibit, to prove that argument wrong.