Individuals can apply for registration of a fixed camera which must be approved by the privacy agency of the state. If it is approved, you can film into public space, but normally this comes with rules like the anonymization of visible faces and car plates when you are a normal citizen.

Without doing this you are allowed to place a camera for constant monitoring at a fixed place if it films your private property only.

For normal businesses the same rules apply, although you might get a camera approved which watches the area around your entry/exit easier.

Those rules made dashcams illegal in most of the EU, but legislation has caught up in those cases in a few countries - but not all yet.

How do we catch a crime without cameras recording everything all the time? That is your question?