Because so many ingredients are obscure in processed food and in medicines. Many ingredients can originate from both animal and non animal sources and so as a Vegan I am constantly having to do without both medicines and food as I cannot be sure of their contents. Veganism is a soulful commitment to the care of animals and the land. It is not a fad and indeed it is a very wise choice politically for those not moved by concerns for animals in this time of climate change. Surely it is a fundamental right to know what one puts into ones body?
All items of food containing multiple ingredients except for the patently obvious and all medicines should carry symbols certifying whether they are safe for vegan, vegetarian consumption. The symbol could be very unintrusive, little more than a tiny mark and so would not be difficult to include on packaging but to those interested parties it would be a blessing.