The problem with perks is that not everyone wants the same thing. I worked for Google, and while the annual ski trip was an amazing perk, I never really enjoyed it. I just don't like group travel very much. I'd probably feel the same way about a Europe trip.
I also found that the longer I worked there, the less the food perks mattered. Right out of college they were unbelievable, but after a few years I wanted to go home and eat dinner with my friends, without feeling like I was wasting the perk benefit.
It is not often a primary factor largely because it is hard to know in advance. Also because of the above. Given a choice between salary and other things, people choose salary.
However, the "choice" is made in other ways. People stay in or leave jobs or even industries for non salary factors. Perks, culture, coworkers, pressure, interest in work etc.
While it may be hard to find cases that people choose a job because of good co workers, it's probably easy to find cases where people leave for the reverse reason.
I knew a company like that - terrible pay, but amazing perks. They really did do stuff like fly the entire company somewhere for a film premiere. Ultimately it's about control. The aim is to make employees utterly dependent on the company in a very basic, primal way, almost literally to the extent of "we clothe, feed and house you" - like a cult. I will always take salary given the choice, it's an honest trade, my time for their money.
your boss flies the whole company to Europe for a week?
I actually worked for a company that chartered the Concord for its 25th anniversary. That happened before I worked there. A decade or so after that, we all find out how unsafe that actually was!
Getting paid 50% of market rate, but your boss flies the whole company to Europe for a week? Awesome company!<sarcasm/>