Why are people okay with giving odd/improper care for animals?

I just remembered this story and it has me all confused again.

A man comes in to get fish after his other fish died, he claims that the person who sold him the fish didnt tell him how to properly care for the last fish and that led to them dying. When I asked who it was that said that to him, he said "oh I dont know their name" (fair, most of my store doesnt wear our name tags for safety sake). I ask him what they look like, "Oh, no its fine, really."

Why would you complain to someone about a worker not doing their job properly and say something needs to be done, but then not want to give the information of who the worker was SO that their misinformation doesnt happen again? We get these people all the time, claiming that a worker said or allowed something that the whole store knows for a fact was not said or allowed. (everyone in our pet care department but like 2 people know how to care for fish since they own themselves, so it would have been easy to pin point the issue) People love to do it for the RX card lol

Anyways, the woman behind him in line heard him and decided to butt in basically agreeing with him and saying that she had to do the research on her own. She asks if he has a heater and he says he is getting one today and shows that he is getting an automatic temperature heater (ones that are at 78 degrees). She then says, "oh no thats not the right one! you need to get one that can be controlled and you can put it to 80 DEGREES" and went one about something like the water doesnt reach the proper temp if the heater is set to 78 degrees...lady..what???

This women claimed she knew proper care cause of "research" yet didnt even know how heaters work. if you set a heater to 80 degrees, the water will be set to 80 degrees, not magically go down to 78...I had to tell the guy that he didnt have to spend 100 bucks on a heater that moment. he was eating up her info like crazy when i could have given him proper information without issue. She had also said this by cutting me off mid conversation of me explaining proper care of fish....

People. Confuse. Me.