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.