Because Nehru wanted to rule India like the British did ..... with an army of 9-to-5 desk jockeys who were intellectually worth less than the office furniture they warmed in that time slot!
All this noise Congress and its following likes to make about Nehru's progressive streak is complete garbage!
Nehru encouraged and promoted Public Sector Undertakings because they could host 100s of 1000s of "B a b u s" who would be churned out from an education system that discouraged and even punished the ability to question and reason!
The British did the same thing because they wanted robotic clerks how would follow orders without questioning them and keep the empire running smoothly!
But why did Nehru want this?
He wanted this so that his dynasty could run its own Indian empire smoothly!