Doorbell - Mandatory?

We are talking about a new building and not an old building. That is why it is incomprehensible to me. However, if I look at the working methods of my developer, it is also quite possible that it was simply forgotten. Do I actually have the right to inspect the calculations and documents of the developer? I often find it confusing how certain costs come about. He should actually be obliged to maintain proper bookkeeping.

Install the doorbell yourself or have BT give you a price...