Should IP cameras be UL Listed?

Occasionally, customers ask me about "Underwriters Laboratories"-listed IP cameras (devices tested and approved by the nonprofit product safety organization). They wonder whether or not a non-UL-listed IP camera can cause a life-safety issue during any life-threatening emergency. All IP cameras should be powered up using a UL-listed power supply, whether a POE switch or a power injector. I am not sure if you can even find a non-UL-listed POE switch and injector, so for all practical purposes, it should be a non-issue. Since all Power Over Ethernet IP cameras lack their own power supplies, they wouldn't be listed with UL. If someone has a good reason to use a non-UL-listed camera, I would love to hear it.