I seriously doubt that!! :roll:
You'd be surprised how many restaurants WILL let you do that if you call in advance. I have an 'inborn error of metabolism' which means that I cannot break down one specific aspect of protein- as a result, I have to watch my protein and limit it very much or I get pretty unwell. I also have several food allergies.
I have absolutely been in the situation where a group of friends was going out to a restaurant that I could eat nothing at, or I could only get a salad or the steamed veggies of doom.
I have been able to, on multiple occasions, call up the restaurant in advance and ask to bring in a meal which they will microwave for me. Yes, they can do that, and they often do. A few times, they have even plated it for me on matching plates so that my company (especially relevant if you're out for business) will not know that I didn't order from the menu.
I have also been able to bring in my own foods to be used in preparing my meal.. I once took in my own low protein pasta to a restaurant while they prepared the rest of my meal (a pasta dish, obviously.)
It never hurts to ask! A good restaurant will go out of their way to serve you- either by helping you create a dish that you CAN eat, or at least allowing you to bring in your own meal. You shouldn't have to stare at a wall and not eat with friends because of dietary limitations!
There are unfortunately restaurants that will not do that. Generally, you're going to have much better luck outside of the US, but I have been to quite a few restaurants in the US in which the person I spoke to did not bat an eyelash at my request!