Even in the 30`s we used single phase, two wire circuits with a hot and a ground wire !! Where is a three wire cord ?? I couldn`t see it in the pics !! There are some things it is used for but not residential lighting in the USA that I know of !!
It does appear to have 3 wires, a double (gnd & hot) and a small ground wire.
And "yes", Mart, lots of residental lighting now uses 3-wire and/or 3-wire w/gnd. It is used for multi-bulb fixtures and mandatory for 3 or 4 way switches.
A ceiling fan with a light would have a 3-wire connection to 2 different switches.
But a single bulb fixture, ..... 2 wires is all ya need. But new Code says ya gotta have 3 to pass Inspection. 2-wire cable w/gnd ..... like the lamp above, whenever wired directly to the "main".