Intercom with outside doorbell to open door?

I want to buy a doorbell with intercom system to open my door. My door will be replaced shortly and will have a digital lock.
They advice my to buy an intercom/doorbell combi like the HikVision DS-KIS701.
That looks like a very nice system, but the problem I have with this is that, if I understand it correctly, the door is opened by the outside unit (door wires are connected to the outside unit). As such they could remove the out-side unit (doorbell with camera) and use the door wires to...

Intercom with outside doorbell to open door?