Good point, WagZ! I have two cameras on the back of my RV, one wired camera up high, and a wireless to keep an eye on my trailer hitch down low (similar to the first one in Barry's post). Most wireless cameras transmit on 2.4Ghz, the same frequency as most other wireless devices and are susceptible to all kinds of interference. I get a little bit of 'snow' on my wireless screen (still, very viewable!), but the high, wired camera is always crystal clear. But at that price, I wouldn't hesitate on buying either camera. I didn't wire my hitch into the backup (reverse) lights - I wired it to the tail light circuit instead using a flat, 4 pin trailer connector, pigtailed into my regular trailer connector. So my vehicle lights have to be on to get power to the camera.
One thing I would want to clarify with the vendor before ordering the wired camera - it is listed as 24V - pretty sure it would work with our 12v systems, but I would want some reassurance!
One other point since we are talking about interference - USB chargers (for phones, GPSs, etc.) can wreck havoc with radios, both music and two-way. I got around that with my Garmin Montana 600 by using a direct power mount;
Amazon.com: Amps Rugged Mount with aud.-power: GPS & Navigation . Some folks don't have a problem at all with interference using USB chargers, others do! I have no idea why!