I didn't realize how important a can opener is in this day and age of easy-open cans.
I needed to cook with grean peas earlier when I realized that the can of peas I bought was not an easy-open can. Being the klutz that I am with a knife, I quickly debated on whether to use a knife or not. I ended up using it, and opening the can partway and then forcing the peas out, resulting in mashed peas.
On hindsight, a household definitely needs a can opener. On hindsight, I could have gone to the neighbor and asked to borrow one. (But then I'd have to ask first if the neighbor speaks English.)