Please help them, they are earning their livings only

She asked him, 'How much are you selling the eggs for?'
The old seller replied, 'Rs.5/- an egg, Madam.'
She said to him, 'I will take 6 eggs for Rs.25/- or I will leave.'
The old seller replied, 'Come take them at the price you want. May be, this is a good beginning because I have not been able to sell even a single egg today.'
She took the eggs and walked away feeling she has won. She got into her fancy car and went to a posh restaurant with her friend. There, she and her friend, ordered whatever they liked. They ate a little and left a lot of what they ordered. Then she went to pay the bill. The bill costed her Rs.1,400/-. She gave Rs. 1,500/- and asked the owner of the restaurant to keep the change.
This incident might have seemed quite normal to the owner but, very painful to the poor egg seller.
The point is,
Why do we always show we have the power when we buy from the needy ones? And why do we get generous to those who do not even need our generosity?
I once read read somewhere:
'my father used to buy simple goods from poor people at high prices, even though he did not need them. Sometimes he even used to pay extra for them.