Things with lots of mechanical parts may break down. Little pieces may get lost. Look for a guarantee. Many companies who claim to have well-made products will promise to fix their product if it breaks. A large grocery store can use that many bags before lunch.
Plastic bags start out as either oil or natural gas.
Oil and natural gas are non-renewable resources. This means they can't be reused, and when they are all gone, they are gone forever. Also, manufacturing these bags adds a lot of pollution to the environment. When you go shopping with a parent, take some paper bags with you. At the check-out counter, ask the clerk to put your groceries in the reused bags.