On public streets, yeah, that's kind of insane. It's pretty common for people to have a dashcam running with a buffer so if you're involved in a not at fault accident or someone vandalizes your car, or such things, you have documentation.
Some societies think that tracking people on public spaces isn't acceptable either. I don't know why it would be insane - if anything, losing all privacy because you stepped out of the house is the insane thing.
Insane would be the fact that i cannot use pictures/video taken in a public setting for my personal use. Publicising these pictures/videos are another thing and that is covered by GDPR.
Where is info on how to install it legally and why this stupid ban on dashcams when GDPR actually allows it (it made dashcam usage easier in my home country as now you don't have to register as data processor because dashcams fall under surveillance). I feel that this is a bad thing - you have a regulation that covers all EU but some countries have their specific laws overriding it and banning things that are allowed under GDPR.