I reckon it's a cute little thing you've stumbled upon, and that is likely to be its date of manufacture. My galv trailer looks just the same now as it did over 10 years ago when it came to us, besides some of the paint coming off (it was painted at some point to make it look less bling and attractive to toe rags). Here's a pic of it full of scrap:
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And it was said to be over 10 years old when we first got it so it's well over 20.
The lights on this are on those stainless brackets on the sides but were originally mounted low down underneath the tailgate. On the back of my uncles rrc and with a full load of hardcore etc they hit the road though so were relocated.
Even the mudguards are galv and are solid.
Trailers are a big thing in Europe - they seem to do a lot more touring / camping / moving about of second hand goods than we do, and where my in laws live in southern France you see them all over and almost all properly built. Not so common here though, and lots on eBay seem to be home made or ex trailer tents etc.
Anything factory built and plated is worth holding on to - think of a crash situation involving something bob from down the pub knocked up from a Capri axle and a bed frame.
If you buy a light board you will at least get new plug and cable too, and might be cheaper than buying all individually. Carry spare bulbs always and make a holder for the plug - dropping the hitch on the plug or running over it with the jockey wheel is a pain in the backside. Cable needs to be long enough to make connection on your secondary coupling (chain) but not too long it's dragging on the floor in use.
Happy camping