Lack of awareness too I guess. But I did see some of my relative's owning dishwashers, so I think it's hesitation rather than ignorance here.
The stronger a light shines the darker are the shadows around it.
Even in Orthodox families they engage servant maid and the vessels cleaned by the servant maid will just washed by the housewife with water for one time before use.
Our maid was not happy to use the vacuum cleaner, because she felt it took more time, and she could finish the same work with her broom and wet cloth mop faster.
'Idhuvum Kadandhu Pogum "
Even this challenging situation would ease