Full Tank vs Fill Ten

The recent hot topic in social media is regarding the BMW driver in a Caltex petrol kiosk.  I do not know who is right or wrong but I think people are angry with the BMW driver who is supposed to be the richer one vs the poorer elderly pump attendant who had to fork the differences.   If the BMW driver were to fork out the 125 SGD, it is still small amount to him vs the poor elderly man.  This is like the old Robin Hood story in modern time.