plastic bag full of plastic bags

Is it just me who has a plastic bag full of other plastic bags in their house? It hit me today that I only think of this as normal because my mum has been collecting these bags since I can remember.
These bags are currently stored under the stairs in the plastic bag our TV came in. However, I’m not sure how much time we have left before the understairs storage can take no more. After all, these bags are never even used for anything, what kind of emergency are my parents storing them for?