"We don't serve free food to our employee, we charge $0.000001 per meal".
Plus it can't be the exact same entity, so they'll have to "partner" with some vendor to create and operate the restaurant.
Access control is vital in a location like a tech company's headquarters. With hundreds of random food trucks coming and going every day, such control will become impossible.
Finally, food trucks are notorious for cutting corners when it comes to food quality, especially any health concerns. I would now want myself or my employees eating from food trucks all day, every day.
But when The Village was zoned, it was explicitly done with street-level retail for a wide variety of restaurants. There are over a dozen restaurants within a 5-minute walk of Facebook's offices, plus a Walmart, Safeway, Whole Foods, and produce market, all of which have ready-to-eat meals.
Something that's left out of a lot of the news coverage of this: it's not a law but a development condition attached to the particular property that Facebook is occupying. When a real-estate developer wants to develop a piece of property, there's a complex negotiation with the local municipality (or county, if it's in unincorporated land) that includes things like contracting for water/sewer/garbage services, how to ensure there's adequate police & fire coverage, how the town will build new roads to handle traffic generated from the property, what's the impact on schools & community services, and what types of dwellings & permitted uses are available for the property (you can't build a skyscraper in the path of SJC airport, for example, nor can you build a chip fab on residential land). Written into that contract is the cafeteria clause under discussion here. While I have some doubts about whether this is a good thing (I've got another comment here where I expressed mixed feelings), it's a contract and not a law, and obviously Facebook has felt that the restriction is not too onerous for the building to be worth occupying.
Perhaps originally they thought they could inspire enough of a public outcry like that seen in this thread to get the rules relaxed eventually... with their recent PR troubles that probably won't happen.
It does make more sense for a development like the Village, but I'm still concerned about the encroaching and escalating intrusion of local lawmakers in a benefit employers wish to provide their employees.
This just means the next massive campus complex will not open in Mountain View. Big profitable companies and their hordes of tax paying employees will go elsewhere, and definitely will not be supporting MTV's local businesses.
Welcome to the wonderful world of unintended consequences!