Currently the Drivers Editor shows this (the blue thing can be dragged to change frame):

But the Drivers Editors X axis is the output of the driver [which can be further tweaked by the curve] not time(frame).
So it seems better to not mix them here, it is just confusing to have two different units on one axis.
Especially since what we really want to look at in X (the drivers output value) can be in a totally unrelated range compared to frames, so e.g. we might be interested in a drivers range from 0.0 to 1.0 and a framerange of 100 to 200, so putting this on one axis just does not make sense. Better to use a separate timeline for this.

Note 2.79 also did not do this.

ref. T91157