We've done surveys and tested household use paints in five LMICs (https://leadelimination.org/projects/)(https://leadeliminati.... 1) lead paints are often cheaper than unleaded paints (in LMICs) because lead paints tend to be locally manufactured and unleaded paints often imported. Also, lead pigments are often cheaper than lead-free pigments. 2) Yes, lead is good at making durable oil-based paints - in some countries with sub-tropical climates durable oil-based paint is popular on the inside and outside of homes, presumably for this reason. It's also easy to clean 3) Water-based paints are much less likely to contain lead and these are also used in homes in LMICs