Nice article Wayne re seatbelt use. You bring up some good strong points and common issues in regards to SHOULD I wear or MUST I wear.
I for one totally agree 100% with most of your points and that at times the wearing of the seat belt is not always practical - especially depending on the nature of work /operation. However I was disappointed with your comment in regards to: It is sad that quite possibly all trainers don't really understand the reality of forklift use and their limitations. I am sure every trainer does the best he or she can, but I have never met one who understands "must" versus "should" in this context. Not one.

Its a shame you feel or think this way! Remember were not all tarred by the same brush!
FYI IN nz:
SHOULD = strongly preferred / indicates recommended best practice (But is not mandatory).
MUST (SHALL) = Indicates a legal requirement under an Act / Legislation. Its Mandatory.

So you see some do know the difference from Should and Shall (Must).
With Forklift Seat Belts I personally recommend you SHOULD wear one! Where its totally practical to do so!
Why would you not use the safety device that's fitted when its suitable to use that said device?.

Cheers and keep those safety issues rolling!
Paul.
(Full time NZ Registered Instructor / Assessor of 15+ years. Operator for 5 years.)