“The story of Detroit’s bankruptcy was simple enough: Allow capitalism to grow the city, campaign against income inequality, tax the job creators until they flee, increase government spending in order to boost employment, promise generous pension plans to keep people voting for failure. Rinse, wash and repeat.”
If we were to measure height of Indian males and plot it on a graph, we will find few are 5’ tall or 6’ tall, majority will fall in between of 5’4” and 5’6” i.e. we get a normal curve ( bell shaped) due to normal distribution, similarly in case of politics few voter subscribe to extreme right ideology or extreme left ideology, most of them are centrist i.e. those opposing political changes which would result in a significant shift of society either strongly to the left or the right. You also have combinations like left of centre (Congress Party) and right of centre (BJP).
This concept can be summed up by Median Voter Theorem, which states that “a majority rule voting system will select the outcome most preferred by the median voter.”
So winning of elections depends on how close your manifesto is to aspirations of median voter i.e. centrist. This forces all parties to include aspirations of median voters in their manifesto. Result is manifestos of all political parties look same.
Any radical change is likely to alienate the median voter and thereby reducing chances of winning elections. Many fiscal reforms like reduction in subsidies, defence expenditure, reduction of staff in public sector, privatization of railways are not favoured by median voter, hence no party is keen to include this in their agenda.
Delhi elections are good example of how median voter theorem works. Voters wanted free electricity, free water, free Wi Fi, all illegal occupation of land by slum dwellers by legalised, women safety, reduction in corruption etc. Manifesto of AAP matched with expectations of median voter, while BJP was working on agenda which was of no interest to median voter, resulting in landslide victory for AAP. Kejriwal played the game quite well and won.