Why are some people (typically younger from my experience) better at detecting AI images than others?

Today, my dad, who is highly interested in AI and is always reading up on it in the news, and who is very up-to-date on new technologies, showed me an image that just didn’t seem right to me. It was of a sad girl holding a puppy, supposedly taken during the flooding happening in the US right now. I told him it seemed AI generated, but he said confidently that it was not. Something about it was just… off. The puppy was too detailed? The little girl’s face was slightly off. The background was slightly blurry? I couldn’t explain it. Later, he came in and said I was correct, it actually was an AI image. There weren’t any obvious giveaways, no people with an irregular number of fingers, it just looked slightly strange to me. And he couldn’t detect it, which is very interesting to me. There have also been a few times my mom did not recognize things as AI generated pictures, ie: of birds. And then there is the issue of older folks online having a far worse time identifying real from fake images. Why is this? It is very interesting to me that he could not recognize what was off about the image, or even that a senior citizen wouldn’t be able, really. Technological prowess may be heavily generational a lot of the time, but why would recognizing that an image looks fake be generational? It seems like an off-putting face, unrealistic textures, and blurry backgrounds would be recognizable by everybody.