Not for any landlord that doesn’t control every business and person in the building.

All it takes is UPS adding facial recognition to driver bodycams or something and suddenly your building has facial recognition in it. Better to just put the warning everywhere and forget about it.

I don't think this is a very good argument. A UPS driver/truck is temporary, and isn't a part of your business. That's like saying you have to put up a Prop 65 disclaimer for your place of business because someones shoes might have a cancer causing chemical in it.

If your place of business is actively adding cameras, and is actively using facial recognition, those are actions that your business has taken. A temporary action of another party should require you to do a disclaimer. Especially if the same action is something they should be disclaiming.

Is it the landlord's job to prevent a tenant from using facial recognition in the tenant's area of the building? I think the tenant is in charge of putting up the disclaimer if the tenant does that.

As for facial recognition in common areas, the landlord can put a clause in the lease agreement requiring tenants not to do that.

If disclaimers are required for facial recognition and a UPS driver has a facial recognition bodycam, I assume it'll be the UPS driver that needs the disclaimer, not every place the UPS driver visits.

True in theory, but is the chemical composition of a building really more complex than the software installed in a building? I feel like theres some 2nd law of supply chains that guarantees that every supply chain --physical or sofware-- will grow in complexity beyond auditability.

The software is in some hardware. The hardware can be seen and removed, and can be known when it's removed.

A chemical can't be seen, and can't be removed.

And even if the hardware is super entwined with the building, making it hard to remove, such as tied in with the HVAC system, there likely will be some toggle switch to turn off facial recognition. There's no toggle switch to remove chemicals.

Eliminating it by a customer is a rather tough sell.

Eliminating either by the customer is very difficult. You can try boycotting or contacting the owner to complain. Even then, removing the chemicals is even more difficult, because even if your boycott gets the attention of the owner, the owner will have a harder time removing the chemicals than removing the facial recognition.