The Author is a transit consultant. He is constantly talking to cities/towns about optimizing their transit networks.
I would guess he is hearing it from politicians and other parties in the areas he is talking to. They will say "Why should we spend $x on a new bus system when uber/driverless cars will solve the problem"
If he's hearing it from politicians/public officials then he should name who made such comments. Since it's the base of his argument that Uber is killing transit, it's important to cite where he heard it.
I would guess he is hearing it from politicians and other parties in the areas he is talking to. They will say "Why should we spend $x on a new bus system when uber/driverless cars will solve the problem"