The main reason I view it that way is because Facebook hires a lot of fresh college graduates who don't necessarily have much (if any) money saved up. To work for Facebook, they're going to have to find a place to live in one of the most expensive areas of the United States. I think it is quite disrespectful to put young people with little money in a situation where they are signing extended leases only to be let go within six weeks.

Granted, Facebook gives out pretty good signing bonuses, so that softens the impact a bit, but still if I knew that the first six weeks were effectively a probationary period I'd make a special effort to find a housing situation where I could pay on a monthly basis rather than entering a six- or twelve-month lease.

Moreover, if I had a family, I'd definitely think twice before going into a sort of six week interview, no matter who the company was. I wouldn't want to put my family through the difficulties of moving there only for me to get let go soon after arriving.