I suppose I should have said "some". Anyway, when looking for the state of the art, we should look at the best value available, rather than the average or typical. The Peacekeeper missile lists a CEP of 120m, although it's now retired. As for Trident, with a 11,000km range, I think we can put it in the same category when looking at reentry accuracy.
In any case, accuracy is gated by navigational accuracy, not so much guidance, as long as your initial aim isn't too bad. ICBMs have a 100m CEP because they're using inertial navigation all the way. Switch to GPS and you'll have no trouble doing better. In the context of SpaceX, getting the rocket to within a few hundred meters of the landing pad is perfectly fine initially, because it can then maneuver to the pad more precisely.
In any case, accuracy is gated by navigational accuracy, not so much guidance, as long as your initial aim isn't too bad. ICBMs have a 100m CEP because they're using inertial navigation all the way. Switch to GPS and you'll have no trouble doing better. In the context of SpaceX, getting the rocket to within a few hundred meters of the landing pad is perfectly fine initially, because it can then maneuver to the pad more precisely.