Why do many historians think that a single central authority ruled in indus valley

labor leaders and organizations had the power to demand it.

explanation:

workers got a five-day workweek because the bcea protects and respect the rights of the employees. labor leaders and other groups demanded it.

congress also has implied powers, which derive from the necessary and proper clause of the constitution and permit congress "to make all laws which shall be necessary and proper for carrying into execution the foregoing powers, and all other powers vested by this constitution in the government of the united states.