I think there is a difference between acceptable behaviour among people going out for a meal, and being a good friend. It might be "acceptable" or justifiable to expect a grown adult to meet you at a different place in a big city, but it's not a friendly thing to do.
But something else occurred to me while reading this thread. Much of the discussion has been focused on whether the other party was rude for expecting the OP to find the new restaurant on her own even though she was unfamiliar with the city. But does anyone else think it's a bit rude to just change which restaurant you're going to without consulting everyone in the party? I mean, even if the new restaurant was next door, unless there was a good reason (e.g. the first restaurant was full, they didn't serve food that someone else needed for medical/religious/ethical reasons), I would be a bit put out if my friends just decided without me that they were changing the agreed choice.