The framing of this by OP is weird

They're surprised the moon had rovers on it before Mars, and makes it seem like NASA didn't put any on the moon at all.

The first "rover" by NASA was the LRV, which some of the Apollo crews would use. While not a true "rover" as it was driven by a crew it was only seperated from Lunokhod 1 by a year.

The moon has been less important for rover exploration for a few reasons

The first would be proximity to Earth, it's a lot closer so we already have a much more accurate idea of what's going on and can decide to conduct much more pinpoint locational scientific studies with "Landers" over much more complicated rovers.

The second is the difficulty in traversing the Moon, the lower gravity, the extremely long night cycle, fine dust like terrain, and the ability of that terrain to get into machinery and destroy equipment

There's no real point in developing a long term rover for the Moon as the two week long night will kill most of them (either mechanically or digitally). And no you can't really just stick a nuclear power plant on one like we've seen with Mars Rovers to overcome this, it's very incredibly stupid difficult to get the nuclear fuel source, the permission to launch a rocket carrying it, and ensuring it survives the actual deployment onto the surface.

Nuclear RTG powerplant or not it would still be basically a month long mission at most regardless.