I got into an argument with my dads friend..?

she fed the dog a burger with onions and pickles on it and before she let the dog have it I was like NO and I told he especially onions are toxic to dogs and she said no! And I said nope they are and she said no vegetables will hurt animals that's why their making dog food with mainly all vegetables In it and I said yeah but only certain vegetables anyways I made her take out the onions then later that day they tried to feed the dog oatmeal with raisins in it then it threw up and is sick and their like I don't know why! And I told them to stop feeding the dog people food... But she still think the people food did nothin to harm the dog