Request received via Technical Support from SCP Bilicki-Dhombres-Osmo:
In the current implementation, if you have a sloped surface (e.g. a ramp) with a difference in altitude between the points along it, there is no direct way of registering that. So, when you register the scans, everything seems at the same level.
It would be great to have this done automatically and to avoid all the additional workarounds to align the scans.