[csense]

I'm thinking of the perks he mentions in terms of a utility function. In other words, how much salary would you trade for paid vacation, company gym membership, company cafeteria, etc.?

Companies offer these things because they think, on average, employees will say "More than they cost the company to provide."

This post essentially reminds people that they should factor in the switching costs for all of these things. It also notes that those switching costs may increase super-linearly if multiple service agreements expire at the same time due to a change in employment.