Non-compliance with the development plan by the neighbor

We are a constitutional state, that is the course of action for people who do not follow rules.

Yep! And the next cyclist who runs a red light will be shot. It’s about an uncovered terrace. As already wrote, the neighbor could also completely legally set up his sun umbrella there and the grill and a pavilion and the beer garden table set and invite the football club every day. Yes, a terrace is not permitted there, but not for reasons of neighbor protection, rather for planning law reasons, which we don’t even know. So we cannot assess the proportionality of possible measures. And if the authority has already signaled blindness, the reasons probably aren’t that serious.

Yep! And the next cyclist who runs a red light will be shot.

I didn't write it that way and I didn't mean it like that. The report will probably be followed by a procedure to clarify the facts. As a result, the terrace will either be removed or it will remain. So the cyclist is not shot from the outset... I am not familiar with the details, but the authority will probably have some discretion in the decision. How that discretion is applied is only known to the authority itself if it indeed comes to that. I wouldn't trust verbal statements at all. I don't think it is the right approach to give up from the outset before people who don't comply with given rules - especially when it really bothers me. By the way: if the terrace is not allowed to be there, the cause of the dispute lies with the builder and not with the one who wants to oppose it. I have the feeling that this is getting a bit mixed up here.

My goodness! If it has to be dismantled, then he’ll just sit with his water basin, trampoline, and garden chairs on the lawn. Right there. And you still haven’t planted a single little plant. The hedge could have grown 1 meter in this last year.

How am I supposed to conjure up a 3-meter hedge in 1.5 years? Besides, it’s nice that he builds such nonsense on the border and I am supposed to figure out how to protect myself?

Your garden, your problem. That you don’t like him is also your problem. The authorities can’t help you with that either. They can force him to dismantle it, but you won’t get rid of him. Don’t you realize that you’ve long since dug out the baking molds?

What motivated him? He wants to sit by the water, which is quite logical to me. That has nothing to do with you. He neither wants to annoy you nor does he know the building regulations.

Don’t you realize that you’ve already dug out the baking molds long ago?

For once, not just said with a "Like": I see both exactly the same way.

Annoying that he hasn't built a fence yet, even though that was agreed. Have you talked to him about it? Maybe you can agree to put up a higher fence and/or hedge together. I would also be annoyed that I have to do it at my own expense now, even though that wasn't agreed. I see it the same way as you. Why should one accept that others think they don't have to follow rules?

I do not think it is the right way to capitulate from the outset before people who do not adhere to given rules – especially when it really bothers me.

Why should one accept that others think they do not have to follow rules?

For me, it’s about proportionality. Let’s stick to the cyclist: You go for a walk with your dog on a Sunday morning and, as a rule-abiding person, you stop at the red light – no one in sight except an unpleasant acquaintance coming towards you on a bike, passing you at 30 km/h. You get annoyed by the ignorant behavior and because you don’t like him anyway, you report him. A resident happens to be standing at a window and witnesses the act, and the acquaintance is punished. In fact, he did not harm anyone. The exact same scene 20 seconds later during the green phase would have been without consequences. Rule violations that harm others should be sanctioned, I totally agree with you. But the terrace itself does not harm the OP. He is not even bothered that it stands outside the building window because he would like to build something there himself. He uses the terrace as an excuse to get back at the neighbor without having to appear himself.

the cause of the dispute

There is no dispute at all. And that is exactly the problem. If the neighbors could argue in a civilized way, the dispute could be quickly resolved. At the moment some conflicts are smoldering in secret and the OP plans secretly to stir things up, which in my opinion leads to an almost irreparable rift.