When i heard this for the first time i was quite shocked, that is some major FUD.
There are specific courses for trained mechanics to attend all of the courses can be undertaken in 5 days. These courses give the attendee the competency training required to work on a EV. once a attendee has undergone these courses they will have the skills needed to work on a EV safely, they can then build up knowledge about each EV. This definitely will not take 6 years!