Consent of neighbors for access length in rear construction

It is still not entirely clear to me why the neighbor is supposed to agree to this. As far as I know, a driveway does not require approval. The carport is the only boundary construction. The floor area ratio is not exceeded.

Are you sure it is about the access and not about the permission for the carport? What is supposed to be subject to approval? I can drive around on my land with my car however and wherever I want.

I have of course only given this statement as non-binding, but both the municipal building authority and the one from the district looked at the situation on their maps and photos from me and said as well as wrote that construction to the extent I have in mind is possible there. So that should basically be possible.

Then go to the building authority with your little drawing and your basic house plan along with a building inquiry. Because then it will be “show the money” from the building authority.

Then go to the building authority with your little drawing and your basic house planning with a preliminary building inquiry. Because then it's time for "put up or shut up" by the building authority

I see it the same way. If the rear development is permitted, the access must also be allowed and not by the grace of the neighbor.

Are you sure it’s about the driveway and not the permit for the carport?
What is supposed to require a permit? I can drive my car on my land however and wherever I want.

A carport is permit-free if it stays within certain dimensions, so that can’t be it.
The last statement from the office is summarized: In new development areas, a driveway length of 10 meters is assumed to ensure compliance with the duty of consideration according to § 15 of the Land Use Ordinance. In the present case, reference is made to driveway lengths of residential plots in the nearby area. If the neighbor has objections, they will be involved in the building application process and can then justify their objections.

Perhaps it is just a general assessment that is always followed to avoid causing problems for the office? Presumably, it is also less work for the office and more satisfactory if the neighbors agree and nobody wants to oppose a building application?

Are the neighbors' objections already queried and examined during a preliminary building inquiry? I assume that only happens at the building application stage, so the preliminary inquiry would only be useful for finding out whether building is possible at all, but not to find out how long the driveway can actually be or where the carport can be located, since that will also be permit-free.

You can explicitly ask about the admissibility of the long driveway.