Pool Light Ground

I have a 25 year old pool and spa, both have 120V lights. I replaced the whole light unit on the pool yesterday and noticed a screw on the upper rear area of the niche. I first thought it was a wire clamp that prevented pulling the wire from the breaker but it looks like the type of screw used to secure a ground wire although it was not connected to anything and there was no seperate ground wire running through the conduit along with the lamp wiring.

I though I read somewhere that there should be a seperate bare ground wire run through the conduit along with the wiring for the lamp. Is that true or necessary? Of course the lamp wiring is three wires with a black, white, and green ground wire.

It appears that this lamp has been set up without a seperate ground since the beginning. The spa light only required replacing the bulb so I didn't need to mess with the wiring or look at the back of the niche there, but I didn't see any bare ground wire running thought the conduit and coming out at the sub panel for that lamp either.

Perhaps is it possible that the niche is grounded some other way, I do know that the body of the pump is connected to a bare ground wire that runs into the ground (the dirt type of ground). I'm located in South Texas incase something is maybe done differently in this region.

Thanks for any advice.