Most companies boast in their OMA the aspiration of best use of equipment.
Some go as far is prohibit NPA and are extremely repressive concerning visuals, as long as an ILS is available.
Funnily enough it's often the same companies who do and actively demand these practice autolands.
An autoland on a non-LVO enabled runway/ILS is not best use of equipment.
To practice autoland, or testcycle on board equipment in conjunction with ground equipment that is not certified or suited to do so, is oblivious.
Thus practice auto land for CatIII on CatI ILS is futile because it does not prove zilch.
It simply should not be done because it's useless and not very intelligent, quod erat demonstrandum.