1) Vegan food is not just for vegans!
Having good vegan options on the menu means the restaurant is automatically ready to cater for a wide range of different customers.
Vegan food also meets the needs of:
# vegetarians, including lacto-vegetarians who do not eat eggs.
# many religious dietary requirements (for example, if the meal does not contain alcohol then vegan food is halal, and is suitable for those who do not eat various types of meat for religious reasons).
# often more suitable for healthy eaters or people watching their weight than traditional meat / cheese-laden restaurant dishes.
# people trying to cut down on meat consumption either for ethical, environmental or health reasons, and any customer looking for something a bit different.
# everyone else! (barring any individual food allergies or intolerances).
Vegan options are a useful way of making your life easy.
2) Good vegan options could win the custom of large groups. If a group of friends, relatives or colleagues is going out for a meal, and one or two members of the group are vegan, they may well all go somewhere which can cater for everyone in the group, including the vegan(s).
Or, put another way, if you don’t have good vegan options, the entire group may well go somewhere else.
3) It’s not difficult and you probably don’t have to put extra dishes on the menu. Every restaurant has vegetarian options, usually a selection of vegetarian options. Just make a number of your vegetarian options also suitable for vegans. Job done.
This is taken from the Vegan Society guide to vegan living, & tweaked.