I know what you mean - the Logic 101 is very comprehensive indeed! It's a great tutorial to dip back into and I recommend it to all my private Logic students & clients too!
Logic 8 to 9 had some pretty minor updates at 101 level - the interface and practically everything else was the same... so there was no need to reshoot an entirely new tutorial. Instead, a few extra videos were shot and some videos edited to make sure it all applied perfectly for Logic 9 users.
As a result, the Logic 9 101 tutorial was offered as a $5 dollar upgrade to existing Logic 8 101 owners. This barely covers the bandwidth cost to download the new version! But we wanted to be as fair as possible.
Of course, if an entirely new tutorial needs to be shot from scratch for say, Logic 10, then the Trainer has to be paid appropriately for their time, effort and expertise - so it wouldn't be possible to offer such an upgrade and the tutorial itself wouldn't be an upgrade but a brand new product.
Hope that makes sense!