The problem is the point of view. Towing a trailer of considerable length requires mirrors that stick particularly far out. If your vehicle doesn't have them front the factory then you can buy clip-ons that attach to your current mirror.

You're not just trying to see your blind spot, which becomes considerable with a trailer, but you're trying to be aware of what's behind you.

It'd be interesting if they went with additional cameras for this. For example, the rear-view mirror is a video feed already. It could stream from a camera you attach to the back of the trailer instead.

I don't have a lot of personal experience with trailers, a few thousand miles maybe. But I've never liked clip on side mirrors. They bounce around/vibrate. A camera system that's optically stabilized and patches into existing displays would feel a lot more natural for someone like me with minimal experience.