> That's essentially correct, but modern tech also makes it relatively easy (and in the end cheaper compared to non-LED) I don't think modern tech is really ne

> That's essentially correct, but modern tech also makes it relatively easy (and in the end cheaper compared to non-LED) I don't think modern tech is really needed for (some of?) the things you list: * we've know about lenses and focusing for centuries (the highly directional Fresnel lens was invented ~1815). * incandescent lights have been around for a century and they were <3500K since the beginning; sodium street lights (<3000K) have been around for decades too It is not so much modern tech that's the thing as modern (better) understanding: we've actually done research into the topic, and that research is more widely known; see for example this report by the city of Toronto on effective lighting (that mentions Dark Sky certification by name): * https://www.toronto.ca/wp-content/uploads/2018/03/8ff6-city-planning-bird-effective-lighting.pdf https://www.toronto.ca/wp-content/uploads/2018/03/8ff6-city-...