In fact, in many ways India can already be said to have UPI. "Farmers" (verified or not, typically rural) have free electricity, fertilizer subsidy, regular loan waivers, ... which were instituted as compensation for a broken market that benefit political cronyism.
This also has the 'benefit' of laundering bribes, without taxes - indeed, a joke about the family of previous Chief Minister of Karnataka (capital: Bengaluru) was that they grew gold in their farms!
Excise on petroleum import affects nearly everyone. I am not only talking about income tax.
Other than this, the soap or detergent or even everyday products we use, contain imported active ingredients and they are taxed at some duty which brings up its price, manufacturer simply adds their own profit margin on top of their costs and passed it onto customers.
Even if most in India have never made payment to customs department, they've still paid considerable sum as indirect duty charged included into product pricing.
If you can just show it to people how much cheaper things will get, they'll give you a chance. This is because Indian voter is very unsophisticated, he will buy your promise atleast once to see if you can really help them by reducing prices.
2 issues.
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.
Also these taxes fund a huge number of programs that will need to be cut down or cancelled which will affect a lot of people (who don't necessarily make enough to pay income taxes). Not really something that any government can do in good conscience if they want to hold power.
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)
Also the prices of fuel directly affects only vehicle owners who are tiny part of the population. It affects everyone else a lot only indirectly, so people don't really complain.
You'll be able to milk rich if there are more mercedes on road, they'll need more repairmen or mechanics, you can be one and charge them for everything.
Right now in India, ultra rich proportionally pay less taxes because of various instruments available to them which aren't feasible to be used by middle class people.
We should shift our focus and let them spend their money, it will end up in one of the countrymen's pocket either way.
Many car makers also do full imports and CKD units for some their lines in India.
If safety is your primary concern I would recommend a fully imported Volvo, while they don't have the Honda, ford or Suzuki kind of service depth , most major cities do have one. Parts occasionally need to be imported. While it may cost a bit more money and time, there is no hassle of paperwork for you.
If reliability is the primary decision point, there are plenty of choices depending on how much city/Highway/rural you want to do, also depends on size, power etc