Physics 303: "pipes are not lossless! Friction and viscous interactions between the entering air and the tube wall will slow down that "shock front" to a highway speed wind in only a couple km." (quote from schiffern post). You may want to look at derivatives of Bernoulli's equation, like Darcy–Weisbach equation.
Plus there is a planned emergency repressurization of the whole tube that would eliminate even that medium speed shock front. Plus a small 10cm diameter bullet hole would imply in less than 1% of the flow of a completely broken tube (a much harder feat to do), per laws of conservation of energy and matter.
As pods travel with 4km or so of separation, at most one pod will be affected. That is much less people than a derailed train.
Plus there is a planned emergency repressurization of the whole tube that would eliminate even that medium speed shock front. Plus a small 10cm diameter bullet hole would imply in less than 1% of the flow of a completely broken tube (a much harder feat to do), per laws of conservation of energy and matter.
As pods travel with 4km or so of separation, at most one pod will be affected. That is much less people than a derailed train.