> In fact every startup I've worked at since 1998 has claimed to offer those benefits. And from what I know, you can even get those benefits at huge companies like Google.
There's a difference between saying you do and actually doing it. No one will say "no, you don't have autonomy -- we don't hire top talent so we have to micromanage; we work very strict fixed hours; you'll be writing CRUD screens for sales people" (I've seen companies claim flexible hours in that "you're have come strictly at 9, but you can leave at 5, you don't have to come in at 8 or stay till 6!").
A start-up can say many things, but e.g., if one place is doing very routine database driven webapps and the other is actually solving far more interesting problems (makes systems software vs. "yet another website", or if they're a web site writing their own search stack and other interesting infrastructure, or does serious machine learning development, leads open source projects, etc...) it's pretty obvious. Plenty start-ups also hire PHP script kiddies (while talking about hiring "rock stars") and other assorted bozos (because they have a project to finish by a specific deadline), while others are more rigorous than Google (from what I heard, Kosmix is one such example).
Google is a large company and obviously there are many boring but business crucial jobs to do there. Nonetheless, at least now, they're fairly explicit what area you'll be working on (e.g., systems programming vs. application programming, sometimes even down to a specific team). Free food and drinks are nice, but that's not why I would still (if I were looking for job) apply there, knowing well others likely give better salaries and fancier titles; the long interview process is a discouragement when other companies are extremely aggressive about getting you to sign an offer, but it has changed now.