Most corporate campuses are located such that public transportation cannot serve it well. They tend to be isolated islands surrounded by parking lots and grass land, with no through street that transit could take that would get from on place to another. Thus the only transit ends at their building, this is okay for a zoo or shopping mall where people come and go all day, but offices tend to be everyone arriving at the same time and then no riders, so to make it worth while to serve you all day you have to be on the way to someplace worth serving. If you are not on the way then people with a choice will prefer to drive just for the one time that the kid gets sick and they have to leave early. (note places where traffic is a problem are also places that are on the way to elsewhere)