The plastic bag is bad for the environment?

People tell me that, when I go grocery shopping, to not use plastic bags, since the plastic bag is bad for the environment.

So, let me get this straight. When I go shopping, I buy:

• 1 pound of sliced ham, wrapped in plastic
• A loaf of bread in a plastic bag
• A gallon of milk in a plastic jug
• A pack of napkins wrapped in plastic
• A Greek salad in a plastic container
• A plastic bottle of mustard
• A plastic bottle of ketchup

And they won’t give me a plastic bag because the plastic bag is bad for the environment?