It's very easy to verify that a company provides free lunches. It could take months or years of employment to determine that a company's "flat management" structure actually exists in a form that agrees with employees expectations of the designation. They are not the same kind of perk, at all. Flat management may not even be a perk! Good management is a perk.

I worked at Valve for several years, and my experience was quite different from what the popular handbook described. It wasn't an especially bad experience, but it wasn't nearly as good as the lore makes it out to be. As you might expect, without written rules or hierarchy, the scene is dominated by social forces. If you put a bunch of people in a room, tell them that there is no hierarchy, then compel them to complete a difficult task, natural human interaction will create a pecking order among other very ugly control systems. Without some rational thought (ie written and mutually-agreed rules and laws), things can turn into Lord of the Flies pretty quickly. It's true that no one tells anyone else what to do at Valve. It's also true that people get fired without warning. Think of it more like the wild west than anything else. Sure, you can be very successful there, but the chaos level might be too high for some folks (me). Check out glassdoor for other anecdotes.