Prior to the rise in frequent use of lakhori bricks during Mughal India, Indian architecture primarily used trabeated prop and lintel (point and slot) gravity-based technique of shaping large stones to fit into each other that required no mortar.
Restoration architect author Anil Laul reasons that poor people used local soil to bake slimmer bricks using locally available cheaper dung cakes as fuel and richer people used higher-end thicker and bigger bricks made of higher strength clay baked in kilns using not so easily locally available more expensive coal, both methods yielded bricks of similar strength but different proportions at different economic levels of strata.
All that needs to be understood is that a poor person could use the local soil to burn slimmer and better bricks, using lesser fuel, to get a home that would withstand the vagaries of the elements and resist erosion and corrosion alike.
The higher caste could afford blending of clays and superior forms of fuel and transport produce over distances.Due to the lack of understanding, sometimes contemporary writers confuse the lakhori bricks with other similar but distinct regional variants.
[1] The concrete mixture of that era was a preparation of lime, surki (trass), jaggery and bael fruit (wood apple) pulp where some recipe used as much as 23 ingredients including urad ki daal (paste of vigna mungo pulse).