The way my (universal) scanner works, is that it measures a reference (no film) which is then set to 0. This gives a direct measurement of FB+F, as well as Dmax - although in bit depth, not density. But the actual units something is measured in in sot important, as long as it's repeatable. And for comparison purposes a film scanner is quite adequate.
Some scanner programs lets you read the density at any point on the preview, that's another neat way of doing it.