Q.Why do developing countries like India need economic planning?

Left entirely to market forces, a newly developing economy often fails to build the foundations that later growth depends on — this is the classic case made for planning.

Market forces, left entirely to themselves, do not automatically deliver the pace or pattern of development that a newly developing economy needs, for several well-recognised reasons that motivated India's (and many other developing countries') adoption of planning:

1. Mobilising scarce resources toward priorities — capital, skilled labour and foreign exchange are all scarce in a developing economy; planning directs these deliberately toward sectors judged nationally important, rather than leaving their allocation purely to whichever use happens to be most immediately profitable.
2. Building infrastructure and basic/heavy industry — private investors often consider infrastructure (power, irrigation, transport) and heavy industry too capital-intensive, too slow to yield returns, or too risky to undertake at the scale needed; planning allows the state to invest in these directly, creating the base on which private economic activity can later build.
3. Correcting regional and social imbalances — market forces, left alone, tend to concentrate investment in already-developed regions and sectors (since returns there are more certain), widening rather than narrowing regional and social inequality; planning can deliberately direct investment toward backward regions and disadvantaged groups. …

Arguing planning is needed simply because 'markets fail' without specifying WHAT they fail to do (under-invest in infrastructure, misdirect scarce resources, widen imbalances) — a vague 'm …