I get so annoyed with the kids' menus at most restaurants. All most offer are hot dogs/hamburgers, PB&J/grilled cheese, pizza, chicken nuggets, and maybe pasta. Restaurants are a great place to try new foods that you might not be able and/or willing to make at home, so why give kids such boring and unhealthy options? Eating out should be a fun adventure!
If regular menu items are larger than your child can eat or more than you can afford, share a meal with your child or having siblings share with each other. You can also ask the manager if they'd be willing to make a smaller/cheaper portion of a regular menu item for your child. Give the little ones a chance to try new things!