Thanks for the question and clarifying the concern.
Unfortunately most source providers of licensed data are also struggling to implement a consistent solution to IDs in this regard, hence why you see some anomalies in Smartform. Where possible we try to adopt source IDs since margin for error increases with repeated preprocessing and transformation of source IDs, and because there is a greater likelihood of getting this fixed at source. However, the concern is noted and we will keep a close eye on it with a view to rationalising where possible (and where this is obvious, since arguably there may be a change in the training regime and therefore a different ID to the single trainer may be warranted) in future.