Vitamin D is not a true vitamin in that vitamins are defined as critical nutrients we cannot manufacture and vitamin D can be manufactured in the body (by most people). It also available to some degree in various foods. It often gets added to milk in the US by the manufacturer and certain fish oils are high in vitamin D, like cod liver oil.
People can make a point of adding more dietary vitamin D or making sure to get a little more exposure to sunlight daily. It is absolutely not necessary for this to only be addressed by buying supplements in pill form and that is probably not even a best practice for improving vitamin D status.
(Edited. Not sure if for "typos" or because "God, I hate auto-corrupt so much sometimes.")
People can make a point of adding more dietary vitamin D or making sure to get a little more exposure to sunlight daily. It is absolutely not necessary for this to only be addressed by buying supplements in pill form and that is probably not even a best practice for improving vitamin D status.
(Edited. Not sure if for "typos" or because "God, I hate auto-corrupt so much sometimes.")