>As stated in another comment, most of the income taxes / import taxes etc affect a tiny fraction of the population. Not really a huge voter base there. Influential and disproportionately powerful - but not enough to swing elections I think

How can this be true? Nearly everyone needs petrol or diesel or gas, and government has increased exise duty on petroleum import which affects almost everyone in the country!

And custom duties also affect others, today if you go to buy a tool - you'll either find Chinese import or some very expensive foreign make tool or crap Indian make tool in most of the case. People need those tools, they'll benefit from low import duties.

Yes but most people aren't aware how taxes affect them even if they aren't directly paying any custom duty or income tax, custom duty is being charged to them indirectly (they pay for a product where the importer adjusts the price according to costs of which custom duty is a part)