One of the issues is that the contracts are overly specific, can be extraordinarily difficult to change, and are not written by experts in the job to be done. There's always tension between "you need to be absolutely specific in order to stop people from cutting corners like crazy for profit" and "your one-size-fits-all instructions will always run into a weird special case where an expert can could just handle it without any extra effort". If they aren't permitted to, by the contract, the job can sit undone for months waiting for the organizations' legal departments to argue about it.