Why people starts blaming Govt be it Mamata or Modi?

Police and media are controlled by politicians. Law is maintained by Judiciary but order needs to be managed by police. Police do not take any action without notifying politicians. They do all the leg work for them.
Also, rules are made in parliament by politicians.

It's very complicated.

Here one of the reasons for the blame game is we don't have the culture of taking responsibility or appreciating when someone takes responsibility.

In personal or corporate life also you would have seen people blaming others for their mistakes or for their inability to achieve what they want to in life.

From this societal mindset people only we choose our politicians so how can they be different.

Also in other countries the politicians are held accountable for what they do, here the citizens don't care much about it except scenarios like this or when they have to face some inconvenience.

Apart from that for national/citizen interest issues other countries politicians work together, here it's almost impossible.

Because everyone wants to take credit for success and blame others for any incompetencies.

Because it's easy. Indians have mastered the art of transferring blame. Get into a road accident? Blame the other guy immediately. It doesn't matter who is wrong, always blame the other. Half the protestors are paid by political parties to create outrage. A sensible common man feels sorry doesn't feel outraged. All those online outrages are usually paid protestors.