It would seem some of the kettles who are calling the pot black may not be doing this
A great number of instructional flights and flight tests were carried out and I assume all those self-employed instructors and examiners read the documents and satisfied themselves that adequate insurance was in place - and if not that they were separately covered themselves and understood the potential liability.
commercial crews check the documents
In an ideal world - that's why one airline's insurance policy almost expired a few years ago before it was picked up at the last minute by an observant FO when the expiry date had been missed by every crew flying every aircraft that particular day!
Unfortunately, insurance is one of the last things on a pilot's mind - partly because he doesn't understand the implications, partly because he trusts that adequate insurance will be in place and partly because he sees only blue skies and wants to go flying!