You can't get enough iron on a vegan diet
Plant iron is absorbed less efficiently, which is a real difference. It is managed by eating more of it and pairing it with vitamin C: and vegans show no higher rate of iron-deficiency anaemia.
The iron in plants is non-haem iron, which the body absorbs far less readily than the haem iron in meat, and it is further blocked by compounds common in plant foods and in everyday drinks like tea and coffee. That means a vegan has to eat considerably more iron, and manage what goes with it at each meal, just to absorb what a meat eater gets without trying, and studies do find vegans carrying lower iron stores. For anyone with higher needs, such as menstruating women, the margin for error on a vegan diet looks too thin to rely on.
Plant foods supply non-haem iron, which is absorbed less readily than the haem iron in meat. This is a genuine difference, and it is why recommended intakes are set higher for people eating no meat.
It is handled straightforwardly in practice. Vitamin C eaten in the same meal substantially increases absorption; tea and coffee at the same sitting reduce it. Surveys of vegetarian and vegan populations typically find lower iron stores but no greater prevalence of iron-deficiency anaemia. Pulses, tofu, dark leafy greens, dried fruit, seeds and fortified cereals carry most of the load.
Presenting only the evidence that supports a conclusion while leaving out evidence that tells against it.
How it applies here: Focuses on one variable (absorption efficiency) and leaves out the outcome data, which is what the claim is really about. Lower absorption and higher deficiency rates are different things, and only the first is true.