My car has only has a mechanical lock on the driver's door. And the manual strongly advises against regular use of that lock for some reason. Supposedly, it is

My car has only has a mechanical lock on the driver's door. And the manual strongly advises against regular use of that lock for some reason. Supposedly, it is just a backup. A quick search of other brands comes up with similar stories and anecdotes of these locks breaking quickly if someone was relying on then too much.