Denial of service attack potential is nice as well: pay $x or we won't unlock your door. As long $x is somewhat lower than what it would cost to replace the lock or fix the damage to the door you might have a buyer.
Back in the kitchen he fished in his various pockets for a dime, and, with it, started up the coffeepot. Sniffing the-to him-very unusual smell, he again consulted his watch, saw that fifteen minutes had passed; he therefore vigorously strode to the apt door, turned the knob and pulled on the release bolt.
The door refused to open. It said, “Five cents, please.”
He searched his pockets. No more coins; nothing. “I'll pay you tomorrow,” he told the door. Again he tried the knob. Again it remained locked tight. “What I pay you,” he informed it, “is in the nature of a gratuity; I don't have to pay you.”
“I think otherwise,” the door said. “Look in the purchase contract you signed when you bought this conapt.”
In his desk drawer he found the contract; since signing it he had found it necessary to refer to the document many times. Sure enough; payment to his door for opening and shutting constituted a mandatory fee. Not a tip.
“You discover I'm right,” the door said. It sounded smug.
From the drawer beside the sink Joe Chip got a stainless steel knife; with it he began systematically to unscrew the bolt assembly of his apt's money-gulping door.
“I'll sue you,” the door said as the first screw fell out.
— from Ubik, Philip K Dick, 1969
(Dick failed to foresee the convenient ability to have everything automatically debited from your Alexoori account. That, and the annual applobe variation so you can't unscrew your door with a knife.)
The door refused to open. It said, “Five cents, please.”
He searched his pockets. No more coins; nothing. “I'll pay you tomorrow,” he told the door. Again he tried the knob. Again it remained locked tight. “What I pay you,” he informed it, “is in the nature of a gratuity; I don't have to pay you.”
“I think otherwise,” the door said. “Look in the purchase contract you signed when you bought this conapt.”
In his desk drawer he found the contract; since signing it he had found it necessary to refer to the document many times. Sure enough; payment to his door for opening and shutting constituted a mandatory fee. Not a tip.
“You discover I'm right,” the door said. It sounded smug.
From the drawer beside the sink Joe Chip got a stainless steel knife; with it he began systematically to unscrew the bolt assembly of his apt's money-gulping door.
“I'll sue you,” the door said as the first screw fell out.
— from Ubik, Philip K Dick, 1969
(Dick failed to foresee the convenient ability to have everything automatically debited from your Alexoori account. That, and the annual applobe variation so you can't unscrew your door with a knife.)