I was on the coop board of my old building, and one of the issues that came up was the expected shutoff of the incoming DC line. We had been using DC for the elevators.

Con Ed had an offer, where they would basically pay for an AC-to-DC converter to be installed, as well as for a technician to do the site survey, installation, etc.

So, yes, DC mains are now defunct, but I imagine a lot of buildings took up the Con Ed offer and are currently running with converters in the basement.

We shouldn't expect locks to be absolutely invulnerable, which I think you might be implying. What we should expect is that locks and other security measures withstand an attack long enough for someone to notice the attack and do something about it.

The problem with these cheap locks is that their ability to withstand attacks is much less than advertised. It may not matter in, say, a high traffic area, but at least the consumer should be aware of how long these locks are expected to stand up to a determined attack.