One key aspect of an organization is you can make accounts not need to deal with there own billing, the way to manage this is under the main organization page you can click on an account and turn on and off organization billing. When it's enabled all charges that will be made to the account will instead be made to the main organization account. This setting can be turned on for each account, this helps organizations that what to share access but not be responsible for billing of all accounts that should not be creating resources.