@greenrun wonderful story, your first lines/paragraph sounded like a Nigerian street filled with hawkers all hustling for survival at each traffic stop in any given location to sell their products to people plying the road.  I like how you also identified how swift and at alert everyone one must be, from the seller to the buyer in other not to be cheated at the slightest of chance.  Since its a traffic that will only last for about 20-30 secs before they start moving, the seller must gather the change first before he or she is been paid, sometimes as pointed out by you they will need to chase the vehicle, if they are unable the customer throws back their goods through the window back to them, some are wicked they will not return it. 

Nice read for a Sunday.