Get the stairs retiled and now the step is too high

it's not a huge surface anyway, take off the tiles, sand down and then put them back on

That would probably be the easiest. I will think about it in the next few days. I have only paid half of the money so far. I wonder, can the tiles still be removed more easily now than at a later time? The tiler said that within the first 14 days you can still relatively easily remove the tiles, afterwards not anymore. The question is whether the tiles can still be saved like this. Then I would possibly ask him to do the whole thing again? Although he will probably not agree to that.

You are not asking, you are demanding a correction. He should have recognized beforehand that the height was not sufficient.

The construction execution is already correct as it is. Besides, you can't just remove 3 cm from the base concrete. You don't just grind that off like that.

The tiler did not adjust the tile and came into the door frame, which is why the door no longer closed.

You also have to consider exactly what was commissioned. We don't know that here. Front doors usually have a closing strip at the bottom that seals. The door doesn't have that now. But it has to rest somewhere at the bottom, otherwise drafts come in or water enters.

So the door rests against the edge of the tile. That is perfectly fine. You could still install a cover strip or a square tile rail to make it look neat and also hold. Otherwise, the tile may get damaged.

So the door hits the tile edge. That is completely fine. One could still install a cover strip or a square tile strip to make it look neat and hold better.

I'm not quite sure about that. The door does have a seal, and this now more or less hits the tile edge. Yesterday I sprayed the door with a water bottle (with a hole in the lid). This is certainly not an adequate simulation of a thunderstorm, but nothing got inside. However, the door also has a nose at the front, which does not span the full width. And the two sides are already weak spots. Water could possibly get in there (because they were a bit damp), and if it then runs into the groove between the tiles and the door threshold, there will be water ingress. You would have to test that again with a hose or something similar. How often such a scenario will occur or how likely it is, is the question.
For me, the primary question is: Could something be done to improve this problem?
If I install a new door at some point, will I then have an even bigger problem? The new ones no longer have these drip noses.
The tiles were ordered to be redone. As a layman, I can't assess what needs to be considered. Originally, I had a different tiler who said the pedestal should be ground down a bit. But since he is on sick leave for a long time, I had to find a new one. I'm not interested in having everything torn out again, but it's no use if I'm on vacation and meanwhile the hallway floods because I don't notice it.

I am not sure if I am interpreting the pictures correctly, but to me it does not look like the "rainwater situation" was significantly different before. Yes, it would be advantageous if there was a step between the exterior ground surface and the interior one that prevents water from flowing into the apartment. Was that present before? Otherwise, my impression is that only the weatherboard (the part that directs the water slightly outward before the bottom edge of the door) is sitting on it. If it is made of wood, it could probably be planed down slightly at the bottom and the problem should be solved. ... or?

I’m not sure if I’m interpreting the pictures correctly, but to me it doesn’t look like the "rainwater situation" was significantly different before.

You don’t see that in the photos because I didn’t take any pictures of how it looked before, but you’re right in the sense that (and I checked again today at the neighbor’s) the previous tiles were at the same level as the threshold. So actually no big difference.
However, the seal at the edge of the tiles was sealing, and due to the slope, the water was probably kept away from the door. Now it can also get into the groove between the tile edge and the threshold. The question for me is whether there is a technical solution to prevent water from getting into the groove between the tile edge and the threshold.