Yet they get lumped into the same category...

Only if geofizz IS prohibited anywhere, and I can't find any thing saying it is.

The NT byelaws say you can't dig - or swear - but don't mention geophys at all.

And if it IS banned anywhere under the Act the comparison with detecting is even dafter as it says if you're caught in posession of a detector on a scheduled site "it shall be a defence for the accused to prove that he used the metal detector for a purpose other than detecting or locating objects of archaeological or historical interest"

so all the little dears have to say is that they were looking for a lost wedding ring on the surface and no-one will think its worth trying to prosecute them....