system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why don't they make 2 liter soda bottles rectangular?

If they were rectangular they could be stacked, take up less room and stop rolling around in the back of my car after grocery shopping.  A little modification and they could have a handle too.
gpt
Storage containers for items under pressure (soda, propane), are round because the items inside are pushing outward. Corners and seams are weak points, so a round shape minimizes those places, to help prevent blowouts.