Its because they dont want you to buy it - they'd rather you paid them to do it
Thats pretty much what i was told when i was looking for the tool to undo the top strut nut without resorting to an impact gun.
(BTW Max, getting coilovers and new discs / pads all round fitted Saturday
Rear pads completely disintegrated at Brunty - didnt even realise til i got back!
)