I also have a cover for my work camera, but it's just to ensure I have a hardware way of turning the camera "off", not because I think I'm going to be hacked.
Besides, I don't think I've ever done anything in front of my work camera that would be of interest to anyone.
I think these are the same thing though. You want to ensure that you have a hardware way of turning your camera off _because_ you know that ultimately you have no control of the software that runs on your laptop. If you had good software assurances you wouldn't need hardware switches. That's the same idea as 'being hacked' (malware, targeted or otherwise) or the threat thereof: that you wouldn't be in control.
To me, its just least-privilege applied. The camera needs to be used when _I_ want it. That's it. The OS doesn't get to decide, malware doesn't get to decide, they don't need access to activate it.
The difference to me is that I don't ever expect malicious intent to be the cause of the camera operating incorrectly. Yes I am not in control in both cases, but only in one case am I being targeted with intent to harm.
Besides, I don't think I've ever done anything in front of my work camera that would be of interest to anyone.