Because no one could ever tunnel through the cement? You realize a lot of these underground facilities were carved out of the rock of the mountain, right?
We need to get the material out. One way or another.
It would take time and somebody would be waiting for somebody to exit from the tunnels.
To go into the tunnels is basically a thirty year operation. That’s the problem with that. Not even the US can sustain a thirty year operation to remove the IRGC from the land.