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Today, about 1mm, which is x1000 better accuracy:

> The distance to the Moon can be measured with millimeter precision.

> The Moon is spiraling away from Earth at a rate of 3.8 cm/year

From: https://en.m.wikipedia.org/wiki/Lunar_Laser_Ranging_experime...

Layman speculation—Using exactly this system (it's quite brilliant!) I bet we could use much higher frequencies due to modern electronics, antenna design, and so forth, giving additional precision, and maybe the ability to measure craft attitude. I could also see additional systems (a laser rangefinder...? or whatever) augmenting it without the mass & energy penalty they would have imposed 50 years ago.

As someone who does modern ranging, you are pretty much spot on.

Fewer and fewer do ranging these days, and the few that does only uses it for contingency situations or to validate GPS receivers during launch and early phase.

The laws of physics haven’t really changed, so I’d guess something similar. It doesn’t seem like their limiting factor was the computers