Restaurants have much to benefit from offering vegetarian meals.  Sometimes even offering just a single item can make a big difference.  They should consider the following advantages.

A vegetarian will come to your restaurant

If you offer nothing at all for a vegetarian, then you are obviously not likely to get many.  Even if they can offer side dishes such as potatoes, this is still not the same thing.  Many vegetarians will be frustrated by this and choose not to come back.  You can lose money on their business.

It is not just the business of the actual vegetarian that you will lose.   Let’s say there is a big family of ten people that includes one vegetarian.  If you have nothing for them, then the entire party might not come there.  Thus it can impact your business far beyond the one person.

A lot of people like to eat vegetarian at times

Even if someone is not a vegetarian, they might still choose these menu items.  Some people eat less meat outside the house.  Sometimes the vegetarian meals are a healthier option that is good for someone on a diet.  For instance, a veggie burger is usually much healthier than a regular burger.  Some people just like the taste.

There are many that are easy to make

It is usually easy to adapt something you have to offer a vegetarian meal.  For instance, if you offer pasta, then you can just offer a meal that is pasta with a vegetarian sauce.  It is easy to get vegetarian burgers and just keep them in a freezer. You just need to heat them up and you can add them to whatever regular burgers you offer.  Some places that offer a lot of burgers will even let you change any of them for a veggie burger.

They are usually not as expensive as other meals

It is obviously cheaper to offer the exact same pasta dish without the meat added.  Many other vegetarian options are cheaper than meat as well.  Most restaurants do charge a little less, but you can oftentimes make a relatively large amount on these meals.

Offering a salad is not the same as offering a true vegetarian meal.  Just as most people would not consider a salad (without meat) as a meal, then many vegetarians would not as well. It can also be helpful to offer a vegan meal as well for those in that category.  Offering several vegetarian  meals gives people choices and might also be useful.  You might see the above advantages with these selections.