Strictly speaking this doesn't make them a true 3d sensor, but rather a 2d sensor with an accompanying depth-map. In order for them to be true 3d sensors they'd be have to transmit information about both the near and far sides of an object simultaneously, for example.
Very true, a 4 dimensional being with 3 dimensional eyes would be able to look inside closed boxes, and see every side of every object at once. (just like we can see every part of a 2d scene all at once)
Arguably, humans are 4-dimensional beings living in a 4-dimensional world—it’s just that one of the dimensions is accessible with much fewer degrees of freedom.
(Not unlike how a seemingly 2-dimensional world of a top-down FPS is actually 3-dimensional, you just have to follow way more rules when it comes to moving in the third one.)
