Physically throwing a person under a big, smelly city bus is the perfect metaphor
for the act of positioning someone to be ground up under the wheels of the ever rolling
omnibus of society
in your stead. The bus carries people. The people's weight is what crushes the victim. This setting up of a patsy has an earlier, more agrarian beginning in "throwing him to the wolves." Someone is going down
, it's not going to be you, so you select a candidate to feed into the system.