It is pretty sad. There is a vast majority of people who are so set in their ways and think this is fine. I can tell you that working at a fish store and dealing with these types of people just make me want to throw in the towel sometimes. I try my best, but then they turn around and get angry with me for telling them these fish need more space as if it's my fault that they grow.
On the flip side, there are those select few that welcome the "new" information I give them about goldfish and hopefully go and tell their friends what they learned that day.
I can't get too frustrated, I guess. My first aquarium consisted of a ryukin and a black moor half his size in a 10 gallon with some god awful decor. We all learn, unfortunately it's mostly the hard way!