The cost of the ingredients will still be pretty low compared to the overall price you pay. A bacon and egg sandwich is about as cheap as it gets to make. It's the time to prepare and serve the food (i.e., staff time) and the time you spend there (i.e., customers per hour → rent) that are the bigger factors.
Quit guessing. Your estimate of food costs is wrong. The bacon and bread at high end restaurants is not the bacon and bread you get at the grocery store. For one thing, the bread at the restaurant just may have been made from scratch and baked in the kitchen a couple of hours earlier. The eggs may have been shipped in from a special farm picked out by the chef. The bacon might have the chef's name on it, too, cause he hand selected it himself when he visited the farm.
And there's nothing frozen and you won't find any microwave ovens either.
Food cost varies but can easily be 28 to 33% of your bill. Now add up how much a couple of slices of your Wonder bread, an egg from your $2/dozen eggs and $5 package of bacon is and then try and figure out why the restaurant food costs so much more.
Let's not forget, too, that, in higher end restaurants, the people in the back room aren't high school kids playing on their phones and dancing to hip-hop while making your food. They are most likely professionally trained with an experienced background. None of them are making $10/hour until they find their "real job". This IS their real job.
How can you tell? You can taste the difference. That's all the proof you need. You may think $15 for a bacon and egg sandwich is high until you taste that sandwich. Then you really know what a $15 sandwich tastes like.
Hey, you're making an awful lot of assumptions here. For the record, you won't find a microwave oven or Wonder bread in my kitchen either. I've had a rye sourdough for the past ~2.5 years. Not exactly sandwich bread, but the point stands.
Making the bread themselves is exactly my point - the ingredients are not the most expensive bit. Staff time is.
Now I don't know the restaurant from the article and how high-end it really is, but for $18 I would expect them to make the bread themselves and not use cheap supermarket ingredients. Staff is still the most expensive part.
Again, you may not be correct. I would have to ask my bookkeeper what our labor cost is, I'm not that involved in mine anymore, but it's not that much higher than food cost.