Investigating Culture Crime in Scotland

Or are they all only
 beach detectorists?

In Scotland, the authorities are reportedly 'stepping up the pressure on heritage crime', writes Alison Campsie ('Meet the team hunting those who would steal Scotland’s history' The Scotsman 23rd December 2019). The article however largely concentrates on the issue of damage done to scheduled monuments

In 2019, around 100 cases of heritage crime were under investigation by Historic Environment Scotland (HES) and police. In the five years before, there were a total of 40 cases [...] Inspector Alan Dron is the chair of the Scottish Heritage Crime Group, which was set up in April to crack down on offences against Scotland’s oldest and most important buildings and landmarks. With 8,000 scheduled monuments to protect, 47,000 listed buildings and 47 protected shipwrecks under his watch, the task is a considerable one. [...] HES and Treasure Trove, which manages finds of artefacts of historic value, are among those who sit on the heritage crime group, which shares information and investigatory updates about offences.[...] Illegal metal detecting [...] had also come to the attention of the heritage crime desk [...] Theft of cultural artefacts are more rare, Inspector Dron said, with some objects heading into private collections and others being lined up for a sale on the black market.

The problem is that Sam Hardy's work suggests there are 1,447+ detectorists in Scotland, yet according to the last report (here)  less than 200 items or groups of items were reported to the TTU as the law requires. That corresponds to one in seven finding one reportable (collectable) item per year, the other six apparently cheerfully brave the Scottish weather week in and week out and take a perverse pleasure in finding nothing but canslaw, modern bottle caps and ringpulls.  Either we have to accept that Scottish metal detectorists are a bit 'weak in the heed', or there are a lot of them finding almost as much as their metal detecting fellows south of the border and are simply keeping it for themselves. Are those acting illegally by not reporting finds being actively investigated by the Scottish Heritage Crime Group? How?