Which floors are suitable for single-family homes? What does the home-building elite recommend?

I'll just throw carpet into the mix...

Out!

What characterizes "really good parquet"? Who in life will sand their parquet floor twice – probably nobody. And oak is oak. The price differences come a) from the name (like with Apple) or b) from special surfaces (well-aged, smoked and treated with 5,000-year-old Inca oil) or dimensions. Otherwise, you can get really good parquet for 25-35€.

Also, for example, whether there are many knots in it (selection of the wood). Then of course the thickness of the wear layer, which is not only good for sanding but also makes it easier to forgive impacts and scratches.

Whereas a tipped bucket or an open window is absolutely no problem, provided the parquet is glued down and not left standing in water for hours.

Here too, the thicker the wear layer, the longer it takes for moisture to reach the swelling substrate layer. And the less chance this has to push up the wear layer, which results in unsightly moisture damage. It may be possible to get good parquet for 25-35EUR. I claim that this is not the rule. I always see parquet with a maximum 3mm wear layer. That’s what I have now, and it is not good. It only takes a pair of scissors falling and I have a notch that goes down to the substrate board. And I have Bembé oak parquet.

8mm solid wood. No fancy floorboards, then it is affordable.

I had carpet. Over time, cleaning was a problem. Furniture left marks and the sun had also faded it a bit.
With shampoo and carpet cleaner it worked quite well. It is more effort than a damp cloth.

I think a lot depends on the quality of the material and the installation. No matter what you have.
In our rental apartment, the laminate was very prone to scratches and had water damage. The installation just had generous gaps.

It may be possible to get good parquet for 25-35 EUR. I claim that this is not the rule. I always only see parquet with a maximum 3mm wear layer.

Up to about 3.5/4mm wear layer is normal and completely sufficient. You also have that with the regular engineered parquet manufacturers in the price range of 100€+. If you want thicker, you might as well go solid.

That's normal and completely sufficient

As I said, unfortunately not for me.
Maybe there's a compensation that I am missing, or it depends on how old the tree was or who knows.

If you want thicker, you can just take solid wood.

I also think that would be best. And then solid wood right away.

I don’t read 10 pages in a forum when I’m on vacation, so short and concise:

is there good parquet for 30€??).

yes! Bamboo parquet!