Because preparing lunch at home and bringing it to work is kind of a nuisance? I eat lunch out almost every day and I don't make anything close to Silicon Valley income. Because I don't want to bother with preparing a lunch at home and taking it to work. And I like to get out of the office for an hour. Doesn't really matter why the employee code to accept it, the point is the employee is accepting something of value, and that value is determined based on prevailing market prices for similar things.