I am not sure how it is in other countries but in this part of the world it is quite common to see a road side hut , tea stall or even restaurants to have their walls painted with advertisements , Its bascially a symbiosis between the poor stall or hut owners who cannot afford to paint or maintain the walls and for small scale business owners who can advertise their products and services at a reasonably low cost .
Of course in the developed cities it is now replaced by Digital hoardings and back-lit billboards. But the old style hand painted walls still has its own charm.
I recently found one such advertisement of our very own MOBA laser leveling system at a village cross road. On further inquiry i was even more overwhelmed by the cost , only 1400 Rs ( 20 Euros ) per wall painting.