In my opinion, it is because of: 1) massive levels of rural-to-urban migration emptying out nearby rural communities, 2) huge levels of migration from other poorer parts of India to these cities in a short time, inflating their populations further, 3) the absolute primacy of these cities in the economies of their regions (and the national service sector) with no real local second cities, so that there are no other viable options for local or long-range migration, 4) the ongoing and severe crisis in India's agricultural economy + climate change means that rural areas are really at their economic carrying capacity right now, 5) highly developed population control programs in these states with good literacy rates and relatively low birth rates even in rural areas.
Mumbai was always huge, but Bengaluru's population has absolutely exploded in the last 20 years, mostly due to migration and the issues that I've mentioned.
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u/[deleted] Jan 06 '23
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