My Opinion About Plastic Bag

What do you think of Grocery stores and shops give plastic bag to the customers??
Plastic bag is made of oil. It takes a lot of money to use it. So if the customer buy just a one thing that is not so big and heavy, clerks don't need to give plastic bag to the customer.
 It is called 'mottainai' in Japanese. 'mottainai' is important in buying thing. Recently, many people bring their own bag to the shop. It's a good trend thinking about environment.