Most vegans don’t need supplements. Just check your b12/iron every 2-3 years
This is false. Your B12 reserves will deplete slowly but surely if you don't supplement. Iron, ferritn, and a complete blood count containing hemoglobin and red blood cell indices should be checked more often than once 2-3 years. Many vegans will need supplements, especially young women.
You also need to check the quantities, as it's often not enough. Also, ingredient lists and nutritional values can't always be trusted.