Non-compliance with the development plan by the neighbor

Ok, thanks for the clarification. I was actually a bit puzzled by your answer, as I have always found your posts to be of very high quality and they have been very helpful to me.

He doesn't even mind that it is outside the building envelope, since he would like to build something there himself. He is using the terrace as an opportunity to get back at the neighbor without having to appear himself.

I was not aware of this point.

Regarding your last paragraph: yes, full agreement, as long as it actually takes place in secret.

Regarding your last paragraph: yes, full agreement, as long as it really takes place in secret.

You can tell this from the tone or choice of words of the OP. To write in the way he does, there must be some background story or other reasons. Otherwise, one would not write so "charged".

Why should one accept that others think they don’t have to follow the rules?

10 reasons: 1. because it often doesn’t matter that others don’t follow the rules 2. because it is more effective to focus on your own wishes and well-being than on those of others 3. because this stubborn question is often the start of a disproportionate escalation 4. because you yourself also often don’t follow the rules and appreciate the acceptance of others 5. because some rules are simply stupid 6. because you have the ability and generosity for composure 7. because you are able to keep YOUR inner Blockward under control 8. because sometimes it’s worth first understanding what prompted the other to break the rules 9. because rules should also be questioned 10. because there are more important things to do right now

He does not even mind that she is outside the construction zone, since he would like to build something there himself.

That's not how I understood it either...

In fact, he has not harmed anyone.

Yes, you could put it that way. The hope is that he learns from the punishment and refrains from it in the future, so that no one gets harmed in the future either.

The perfect place for a compost heap and a huge insect hotel. Even at the risk of repeating myself.

That's not how I understood it either...

I did - in the subordinate clause, the OP mentioned that he would like that too.

Yes, you could see it that way. The hope would be that he learns from the punishment and refrains from it in the future, so that no one gets hurt in the future.

What is someone who hasn't caused any harm supposed to learn from a punishment except that the person who initiated it is to be regarded with caution. The concept of "punishment" has zero effect in such cases and serves more the satisfaction of the punisher than the matter itself.