Kerala has the highest level of social development than any other state. You will not find criminals coming out to vote for a non elected prime minister. You will not find the levels of corruption and fanactism you can observe in Gujarat, Maharashtra or Delhi.
Admittedly, it is community regressive (loads of shame) and filialy progressive (loads of honor) so we have the largest rate of suicides per capita - more than Lanka and Japan put together.
i.e. why we rarely (except in Mozzie) north, we do not elect criminals or laloos or congress to parliament.
The choice of communism by the vast majority is because the basic amenities (average) is much higher among the poor of Kerala than the rest of India.
The choice of communism is due to our higher rate of literacy and due to ideals (nobody else has any) - also due to the lack of choice (alternates are Pasta Gandhi and Monkey Dal).