How about an ad when you ring the doorbell and only after watching/hearing it will the occupants get notified.

Yes you could install a credit card reader on the doorbell and shame the owners by alerting their visitors to the fact that they've not paid the bill, but informing them that they can ring the bell for a minimal yearly subscription.

Can I make the doorbell reorder laundry detergent for me too?

I don't see why not.

They should change the doorbell noise to “cha-ching”.