It varies a lot.
Each shop has it's own terms so you have to read carefully every time you do a new one. If you do the same one enough times, maybe you only skim to check there aren't changes.
Sonic is written as a one person activity. You can have other people with you but they don't get to order with you. That's pretty awkward unless you really only want the burger and someone else will be satisfied with loaded tots and a drink.
Some restaurant shops require a guest and dictate what you order to some degree. Maybe the reimbursement is ample to cover you both and gives some flexibility to your choices. Some require a guest and let you order whatever and they don't pay enough to cover even the cheapest meals. Some allow you to bring kids, others don't. Some don't require a guest but prefer one and there may be two different reimbursement amounts depending on whether you have a guest.
FAR too many different scenarios to generalize about what is "normal".