Don't hate!

I'm trying to understand why it is that restaurants make you feel like shit when you try and order healthy.
Honestly, I am so NOT one of these people who expect special treatment, nor do I try and make them prepare me something not on the menu, or custom-tailor anything to my needs. Usually what I will do is pick something that looks the closest to what I will allow myself to have, and then go from there.

My usual fare is a large glass of ice water w/ lemon (as Alison puts it, 'poor man's lemonade'), a salad of some sort with vinegar and Splenda, (not hard to accomplish as most restaurants carry oil and vinegar for salads) and then an entree involving a sort of steamed veggie and grilled meat. MOST restaurants carry things like this.
So why do I get dirty looks when I order these things?
Am I the only person on earth trying to eat healthy? Are the vials of vinegar really high up on a shelf?
I'm tired of the discrimination. Grrrr.