The legality is that your old company have done a risk assessment and ordered all items to be checked before sale, a prudent move considering as they didn't know if the item was safe when purchased and need to cover themselves for sale of the item.
As for the training, again, the recommendation is that a "Responsible Person" does the work, however, if someone took them to court and their response was "well we did 5 minutes device training" and the court found that inadequate, they are responsible.
You cant better experience and just formal academic training is not adequate, its only my opinion, but in a society hell bent on claims and still (according to the internet) around 100 people dying each year from electric shock, its better to pay 0.59p per item and have a good nights sleep in bed!