Well, my curiosity was raised.
I currently use the YUASA SmartShot 900 Battery charger-maintainer. Like Miles, I have 3 of these small and very reliable chargers.
I did not lift the seats off my Bikes to check the in-line fuse AMP rating on the cords, so I looked at a spare un-opened YUASA SmartShot 900 Battery charger through the clear plastic and the in-line fuse housing states 3A, I then looked at a new spare plug with the in-line fuse and it has a 7.5A in it. So there are several plugs out there. The last Bike that I sold had a 5A in-line fuse on the cord that connected to a Ctek charger, I assumed that this was the standard. Obviously it is not and they are available in a 3A, 5A, 7.5A or 10A. Like Miles, I have never blown a fuse on any tender cable.
So I just learned something today that ALL of my battery tender connecting cables had/have 3 different Amperage ratings.