I know some restaurants that try to push the limit on their mark-ups, but for the vast majority of restaurants out there - the mark-ups are fair and reasonable. Yes, consumers have immediate access to pricing via their phones, now, but there is a lot that goes into running a business like a restaurant and as such they need to generate profit from every possible channel. Wine is sometimes as much as 30% of a restaurant's sales, and paying attention to the value of that section is quite important to a lot of the places I deal with. No one just marks things up without giving very serious thought about the prices being charged and how they will compare to other restaurants AND to retail. In my experience there is little gouging or "greed" happening, just honest, reasonable mark-ups.
The Lowdown on Restaurant Markups - Wine Enthusiast Magazine - May 2010