I don't think many folks think about food as much as the folks here do. That said, I can think of folks with dietary restrictions on meat (be they religious, social, or other reasons) that would never think to ask about the stock of a vegetable soup or whether the pie crust, french fries, or apple fritters were made with animal bits.
I do and after this thread I'm even more vigilant.
The problem is the vegetarians I know are not dogmatic. They enjoy time out at restaurants with their family,colleagues, and friends. They don't insist that every meal out is at the vegetarian/vegan restaurant. They date, love, and marry people who eat meat. They know, even if they don't want to think about it, that their food, in most restaurants, is cooked with vessels that held animals.
Heck, I've ripped the faces off of living creatures (soft-shell crabs) to serve them to my husband. He told me they were great. I told him I couldn't do that ever again and I didn't become a vegetarian for animal rights reasons.
FWIW, we serve our dog the raw diet. So plenty of other animals get sacrificed for my dog to eat what we consider the optimal diet for her. Just ask
Pat and John Sondgeroth of Heartland Meats, I'm their best vegetarian customer.
I like the highfalutin places that ask if there are any allergies or dietary restrictions. Someday that may well trickle down to the Mom & Pop venues. I don't think that is a bad thing. It's a way of showing care for your customers.
It's no different than having a host ask if there is anything you don't like, not whether you have an allergy or dietary restriction. No one wants to serve or prepare a meal for folks to discover the thought of eating tongue, pig's blood, or intestines is enough to make their guests vomit & scream. Many can't stomach the thought of eating young animals (lamb, chicks, or veal). There are certainly plenty of meat eaters who would never in a million years eat young animals or organs by choice. Most of the non-food loving world is more than willing to accommodate those folks. I don't see it being too big of a deal to accommodate those that don't want to eat animals, especially if you are in the business of serving food.