The reason why the key is the owners responsibility is a lot of strata are holiday lets or renters and so if the strata were responsible for the keys and remote just imagine if the holiday renters never bothered returning the keys/ remote when they left the strata would be lumbered with the cost of each replacement (some can cost $300) and so in QLD (and I guess the same applies throughout Oz) it’s been ruled that it’s the owners responsibility.
This makes sure the owner has in place a procedure to recover the key / remotes or else the owner has to cough up the cost of a replacement.