What’s the primary reason for not paying income tax? Illegal tax avoidance, too low income to qualify for paying income tax, or smth else?

Edit: found an article about it

What Uttar Pradesh lacks in tax rate, it makes up with number of tax payers.

I’m a little ignorant here so happy to be educated, but are the higher tax paying areas also the ones with the biggest religious minorities? Does the federal or state authority set the tax rate? I find the history/culture/ethnic make-up of India fascinating, very keen to visit one day.

Andaman and Nicobar Isles can probably get more tax revenue if the North Sentinelese pay their fair share. But they’re more likely to shoot you with arrows instead, being an isolated civ.