The difference here is that these are not royalty, just an entire community (a caste) of people who made the money by trade. Every chettiyar I know still has their “big house” in karaikudi though I assume these are not as opulent as these old mansions (most of them spend at least a month in these places every year). The interesting part is how most of them are indistinguishable wealth wise from other community folks even though they clearly started with great wealth a few generations back.