G'day Flashing,

Said detail of course meaning that they would have to know what each piece of gear was and what its function is.
I think the required detail aspect is not the issue. Rather, I think it's much more simple than all that.
In the very same fashion as the vast majority of their Punting compatriots, I very much doubt the majority of Stewards would have any idea at all what a Murphy Blind was to begin with let alone what it is/was meant to do.
In fact I doubt that most onlookers, officialdom, participants and public alike...have any idea at all of what various bits of gear added to or subtracted from a given horse's rigging does/is expected to do/is designed to do. That's why the whole Gear Form and gear change notifications are such folly. If a horse goes out in full blocks one week and it goes out in a wide open bridle the next, I guarentee you that virtually nobody notices, Stewards included.