Even if there was a standard format, there is nothing stopping manufacturers to impose one of their own. Every time there is a new reader, there is an other language sometimes accompanied by an other format.
We've had a computer platform war that is still going on even in this day of open communication. The only communication standard considered worldwide is HTML. There is nothing even remote attempting to take over. Why not use it? Because it's free of charge. A captured market is what is sought by every device manufacturer.
Holy '$DEITY' to quote our friend.