This is a common problem with companies. I've worked as both contractor and staffer. Being a staffer is always better in terms of what perks the company offers on terms of day to day perks. Contractors may seem to get paid a bit more on a per hour basis but when you add up all the company perks, it's always less.

Also, staffers always see temps/contractors as outsiders. It does not matter how long they have worked together. It's a strange dynamic. I try to avoid contract/temp work if it's going to be a long term position. It's never pleasant.

Facebook is not the first and it won't be the last. Contractors/temps are a benefit to companies since the company can have a flexible workforce they can increase or reduce with little friction.