Democracy works best when equality is homogenous across the population. With a population with lot of socioeconomic inequality, it ends up being a tool of exploitation in the hands of those already in possession of a larger share of the wherewithals.
Goods delivered by an authoritarian regime depends on the person and/or organisation wielding authority. Democracy averages out the good and the bad. So while a democracy gives an average leader most of the times,authoritarian is more likely to give 4 megalomaniacs for 1 decent guy at highest level.
A large proportion of the population is now coopted into corruption. Most people are not just victims of corruption, they are a cog in the corrupt machinery. This is a major reason that large scale initiatives fail, because they are designed with the assumption of most people being honest.
India is the most heterogeneous society. Fracture lines are many—religion, region, caste, language, socioeconomic status, skin color, political ideology being just a few of those. From time to time, these get exploited by politicians. As a result cohesiveness necessary for collaboration is missing
With so many things obviously failing and in a shoddy condition, most people have not only given up the pursuit of perfection, they are not inclined to contribute to keeping the systems running, indeed they are not even averse to adding to its delapidatedness.
Conceivably we can overcome all the flaws outlined in the other premises here, within the current democratic system, using the extant democratic institutions.