I do know the shed you mean Slackie. However let's imagine a pilot from someplace south of Ardmore transitting through the Mercer MBZ and being unfamiliar with the "green shed". Her or she would have no idea where the aircraft are using it as a reporting point. Given the MBZ is not that large, surely it would be better to simply reference your position to Mercer AD?
I think I have suggested it here before, but those pilots who have little experience or knowledge of airfields other than AR should take a trip to Paraparaumu. My hat goes off to the operators there who, while undoubtedly on opposing "teams" exercise good airmanship and courtesy to all. I was impressed last time I went through PP to hear pilots offering to extend downwind so as to let other operators line up and take their time teaching the student pilot how to commence the takeoff roll without some balding CFI yelling at them to get off the runway!
Itai is quite correct - if the standards that the likes of AFS aspire to are "industry standard", said industry is in trouble. Thankfully there are other places in NZ where airmanship and professionalism are still taught. It's up to the industry to weed out those who have been through the lower standard processing plants and send the message back that what they produce are simply not good enough.
Heading off on a tangent other than the one I'm on now, perhaps the release of Cessna's 162 will see some of our smaller aero clubs start to recover. That's where we can see some decent standards taught. As Itai mentioned, it's up to industry now to ensure the changes to Part 141 as proposed by the AIA (oops I mean CAA) will permit the smaller aero clubs to operate the likes of a 162 within a sensible legal framework that will allow them to do so economically. If not, if the principle proponents of this rule change (the processing factories) get their way, there is no way our accident rate will reduce.
(For our goaty-bearded boy racer AFS fraternity, the AIA stands for "Aviation Industry Association" - it's a body of aviation-related company officials out to better their own bottom lines at the expense of standards and safety).