Automated watering at night - does anyone do that?

Alternatively, consider that we are increasingly threatened by water shortage situations in Germany as well, and maybe we shouldn’t waste dozens of cubic meters per year on green but ecologically almost worthless lawns...

The diesel-driving gas heater is actually becoming green after all, I really like that!

Causes of dry and brown lawns are mowing too short and too often.

Lawn robots do their part. I myself have the best and greenest lawn. Yes, that also depends on soil quality.
Nevertheless, you don’t have to mow three times a week. Just leave it a little higher and mow when rain is in sight.

How high do you let your lawn grow and how often do you water currently?

But the rain often comes as heavy rain

Please remember that the streams and rivers are also happy when water flows in; this is also important for shipping on the large rivers. Moreover, farmers also pump their water for the fields from the rivers (of course not for cultivated food). I wonder what would happen if everyone collected all the roof water. What would then flush the sewer system, etc.? And sewage treatment plants also discharge the treated water into rivers...

Or you just water every 2 to 3 days during the dry months. One (or at least we) wants to walk and sit on the lawn. And preferably barefoot. That doesn't work with just gravel and/or herbs. In our sand, everything needs water more often than in clay or other firmer soil. Except cacti etc. But walking on those is bad.

You can walk on it. If you absolutely want an English lawn, that’s your decision and then you just water every 2 days. At least as long as it’s allowed, especially in Brandenburg you hear a lot about water shortages. But please don’t blame your soil for choosing completely unsuitable planting. Nature has adapted to every climate and soil over thousands of years and accordingly found what suits each location. And if you want to look beyond your own nose, I would search for the term flower gravel lawn. That’s actually intended for gravelled driveways, paths, etc., but will certainly also grow excellently in sandy soil.

I wonder what would happen if everyone collected all their roof water.

Meanwhile, the municipalities actively encourage this. You do pay fees for sealed, non-permeable surfaces. Unless you direct it into a cistern or have permeable paving or similar.

then show your "best lawn" Proper lawns are mowed every day. Preferably with a reel mower. And not everyone wants a lawn that is considered tree cover. Especially a robotic mower improves the lawn through daily cutting and you save about 1/3 of fertilizer. The height can also be adjusted ;) When it's dry, even 4-5 cm height doesn't help. That's no longer a lawn but a meadow. Mine is kept year-round at about 1.7 cm.

Sorry, but a meadow is about waist-high and is mowed twice a year. These are completely different types. And it does help the lawn very much during drought if, first, you don’t mow too short and, second, you don’t trim it every day and stimulate the grasses to grow. With less growth, by the way, you can also save the fertilizer and the grasses need much less water. From about 5 cm upwards, the rosettes of the herbs also survive mowing. Of course, you can’t play golf on it so well and you probably won’t win the prize at the English garden show either. But it is and remains a lawn and not a meadow