There are many areas in strata schemes that are common property but only limited access is allowed. Communications and electrical switch board cupboards being an obvious case. On the other hand, in some states, incl the balcony is common property but only the owners of the adjoining lot have access to it.
Why isn’t it lot property? Because balconies profoundly affect the look and even the physical integrity of the building and it’s easier to maintain them and set standards for their use if they are common property.
The lift lobbies in this building fall into that category, which is common property but which is normally only accessed by the adjoining lot owner and so it feels like lot property. But the lot owner does not have the right to forbid legitimate access by agents for the strata scheme or, indeed, do whatever they want on it.
This is why smoke drift has become an issue in a lot of buildings; the strata scheme has the right to create by-laws covering the use of common property and people affected by smoke drift get frustrated when their neighbours on the committee or at an AGM refuse to do anything about it.
So the person on the top floor who doesn’t want tradies traipsing through “their” lobby should be quietly reminded that it’s not theirs exclusively and in an extreme situation, they could be ordered to remove all their stuff and repair all the holes in the wall from their picture hooks.
However, the committee is not going to do that but maybe they will let them know when tradies require access and they can sit on a deckchair and watch them pass by, if they want. But if they do so stark naked and/or shouting abuse at the workers, they could get a notice to comply with the by-law that says you can’t behave offensively on common property.
Common property isn’t always just common property but common sense is always common sense.