How much a polythene bag cost to a shopkeeper?

In Bangladesh, we can’t think of shopping without a polythene bag. I guess it’s not costly that shop keepers easily give it to the customer free. But some very alert shopkeepers don’t want to expend more or want to use less than it needs. It’s not because of awareness of the environment, it‘s to save money for their own. Let me tell you what I faced. I went to Agora and buy a fish (Rui). I request them to cut it down and deliver it to me. They did and gave it in a polybag, which was covered with fish blood. I said, please put this bag into another polybag that I can hold it and take it home with other things. The salesman denied it. He said, no worry madam, on the counter, other salespeople will give you a cloth bag, and you can take it with that. But I again said, with cloth, blood will come out and mess my dress and other things, please just give me a polythene bag. But that salesman denied. Then another salesman also requests him, please give her a bag. The first salesperson gave me a polybag and I could hear what he was saying to the other salesman, "this way how can we do the cost-cutting."

I generally buy eggs from a common shop. He has the assistance. Whenever I buy eggs I asked him, please give me two poly bags that the eggs will remain good on the way to my home. He doesn't. When he handovers the eggs to me, I again asked him, please give me another polythene bag. He didn't. Then I had to ask the main shopkeeper. He gives instruction to his boy, and then only I can have two poly bags.