Some of the comments here suggest that the Google's perks are bad because they corrode work/life balance and encourage employees to stay longer.

Having worked at some of the FANGs, I can say that this effect of these perks on work/life decisions is very very small. Most people enjoy the perks and do what they were going to do anyway. Most of my teammates won't stay for free dinner because they'd rather spend time with their friends and families. Most people work from home all the ~once/week.

When work/life balance is bad, it's because of a desire to perform or managerial pressure; not because you get free food and an on-site dentist. Generally the perks are conveniences and genuinely nice to have, and if they are part of a sinister plot to exploit workers, they are pretty bad at it.