Short version is that MacOS made it so root cannot modify certain files without rebooting, disabling security and then booting to change those files. It can also stage changes to reload on boot, so for example, when you get a new version of the Zoom client, you actually have to reboot to make the camera permission go into effect. It's probably safer, but as a user, having to reboot just to turn on the camera is... MS Vista like...
I've been running the latest version of macOS and I've never had to reboot to enable camera permissions for any app. I haven't had to do it on fresh install or upgrade. The only thing I've had to do is close the app and open it again after giving it camera permission on first install. Subsequent updates seem to keep that permission enabled...
