The two reasons I think it's not that black and white is: 1. This brings up the question of being able to agree to a contract before the contract is written wh

The two reasons I think it's not that black and white is: 1. This brings up the question of being able to agree to a contract before the contract is written which makes no sense. 2. If it's legal then why don't all companies do it. Instead, companies like Google regularly put out updated terms of service which you have to agree to before continuing to use their service. Often times you don't realize it because it's just another checkbox or button to click before signing in.