I wonder why not use those simple laser rangefinder things and instruct the user to put CD-tracking like servo steering suitable retroreflectors at fixed-relati

I wonder why not use those simple laser rangefinder things and instruct the user to put CD-tracking like servo steering suitable retroreflectors at fixed-relative-to-workpiece locations. 2 should suffice for planar work. Probably "tape money" reasons for that engineering trade-off...