Proper handling of entry device is key to keeping apartment building secure
The landlord is not obliged to change the lock on the tenant’s door. If the tenant asks the landlord to change the lock to their own door, or if security concerns caused by the tenant require changing the locks, the landlord is entitled to insist that the tenant pay for the cost of that.
Some tenants lose keys from time to time, especially in a large building where there are many tenants. Landlords do not usually change the front door lock just because some tenants have lost their front door keys.
The front door lock is only a modest security device in any event, because it is usually easy for someone who looks like they belong in the building to enter the building, even without a key. Tenants habitually hold the front door for other people as a matter of courtesy.
If it appears that there is a break-in problem at an apartment building that has followed the loss or theft of a set of keys, then landlords do sometimes change the locks to the building. That is a substantial expense, and a nuisance for both the tenants and the landlord. The tenants need to be notified, and then when the locks have been changed, the tenants need to be given a new key (or two, three or four if they have that many.) Tenants who miss the time of the exchange find themselves locked out and are naturally not happy.
A claim against a tenant would probably only succeed if a particular tenant had repeatedly lost the front door key or has allowed copies of the front door key to fall into the hands of undesirable non-tenants, and the landlord can prove that a spike in break-ins followed the improper handling of those keys.
The claim would be under section 89 of the Residential Tenancies Act, which allows a landlord to claim compensation for the “repair of damaged property” if the tenant has wilfully or negligently caused undue damage to the residential complex (or the rental unit.) A landlord would argue that the improper handling of the front door key has damaged the front door locking system by making it insecure.
The rules discussed above apply not only to keys but also to key fobs or remote entry devices. However, key fobs generally limit the problem since the landlord can usually disable the lost fob, so that the replacement of the lock is not necessary. On the other hand, the cost of replacing the fob can be much more than the cost of replacing an ordinary key, and more than the cost of replacing a Medeco key, which reputable locksmiths will not copy for anyone other than the registered owner.