The doctrine of governmental immunity from tort liability historically stems from the concept that "the King can do no wrong," and that a vassal could not be heard to complain against his master.
John W. Latella,
Governmental Immunity from Tort Liability: Pennsylvania's Trend toward Abolition,
Duq. L. Rev.
Available at: https://dsc.duq.edu/dlr/vol4/iss3/5