Hawkers might just love the every cent they had cheated you of. (well not all, but generally- especially the Singapore ones)
Within a week I have met 3 stingy+shady hawkers:
At one of the Jurong Point foodcourt stalls that I purchased a bowl of noodles from, I requested for more vege. The first time I politely ask the cooking auntie, she ignored me. The second time I ask her, she changed the subject, "chi de?"/ Eating here? She said. The third time I called "Auntie," Yet Again she ignored. I called her again, and finally, she said (in chinese) "There's a limit to vegetables, its expensive these days."
I own a starbucks tumblr which looks tall, but the walls of the bottle are thick so its narrow inside- not really much total volume. I used it for bringing coffee/tea into the studio so I will not get caught illegally eating/drinking and so attracting the rats that they (really) found. It also minimizes the mess done but styrofoam cups and the sustainability of it.
Anyway, hawkers always think that my bottle is extra tall of having bigger volume. They won't fill the bottle straight away until they reason out how much they should charge me or fill the bottle.
The first drinks stlall man used his own styrofoam cup to fill in the drink, then told me to fill it in the bottle myself. It was exactly the same amount. Why waste a disposable cup when you can just give me a little more of that water?
The second drinks stall lady took a look at my bottle and gave me a choice:
1. Pay 60 cents for full cup
2. Pay 50 cents for half cup
I know its only a 10 cents to cause a rise of 50% in drink volume (I don't know what kind of elasticity this is)
But sorry, I won't let you have an extra 10 cents for you let go of more water in that huge dispenser.
She filled up 60% of the bottle anyway, that 10% more probably from me saving her one styrofoam cup. I forgive poor hawkers, for 10 cents might mean a world to them.