I visited a friend once, who had a fancy goldfish swimming around. In one of those large brandy glass shaped vases. No filter. Nothing. They just tipped out most of the water daily and topped it up with fresh - from the tap.
I had a good chat with her about it when she asked me about my tank set up and realised that it needed sorting out pronto. So they bought a tank and she proudly sent me a photo of it.
It was one of those picture frame tanks. Approx 3ft wide but only a few inches deep!
In her eyes, a much bigger setup than the fish had been in, and it matched the decor.
And then they went and got 2 more fish to keep the original one company. She wasn't terribly happy when I had to point out that it still wasn't anywhere near as much space/water as the fish needed.
I hang my head with shame remembering how I had a fair fish or two in a small unfiltered tank as a kid, to be fair, but that was pre-internet in your homes (yes, I'm that old!) and it being really easy to find the info you need to keep the fish properly.