Meat and eggs. So you need eggs. It’s also present in dairy.
So the parent’s claim is an argument against unsupplemented veganism, and your counter of vegetarianism doesn’t address that. Massive difference between the two diets in terms of needing to supplement or not.
Oh, you didn't click through, maybe. Or missed that the linked page included millions of vegans, too, in the same chart.
You can sort by any column, and see that the U.S., Brazil, and Japan have the highest number of Vegans, while Mexico and Poland purportedly lead by percentage, though those two are disputed.
So the parent’s claim is an argument against unsupplemented veganism, and your counter of vegetarianism doesn’t address that. Massive difference between the two diets in terms of needing to supplement or not.