Their health insurance package is extremely expensive and a huge amount of money goes into supporting campuses with buses for commuters, full meals, laundry service, and so on.
I wouldn't call health insurance "extremely expensive" in the context of Google SWE salaries. On average it probably costs on the order of $5-$10k/head/year at most. My very loose upper bound estimate is $50k/year for all aux benefits and bus/campus costs.