Carnists will claim that they have non-vegan friends or family members, and that would put them in an uncomfortable position if they couldn't find something to eat at a restaurant.
It isn't a good enough justification that it's going to be hard to do the wrong thing. Sure, stealing money is easier than earning it. Is that worth it to you? Even so, it doesn't even matter because
Even at most bar-type places, you can get a plain baked potato with steak sauce (check that it's vegan - most are). At most places, you can also get a salad - ask for more veggies instead of cheese/croutons/egg. Oil, vinegar, and salt are a safe bet. Also, just ask a server for recommendations. If you can't find a single dish - you can always eat before you get there. Don't worry, vegans know that carnists would do the same if you invited them to a vegan-only restaurant.
Also, you can always throw out suggestions to go to a (slightly) more vegan-friendly place. Most Asian places will have tofu, and most Central/South American places will have vegetable dishes such as fajitas, and most places will have some pasta dish. Even so, it's usually only hipster tapas/bar places with only 10 overpriced things on the menu that will offer truly nothing vegan.
Wait, is vegan food too expensive or are you eating out at restaurants?