Trader - I can only agree. The big problem with fatigue is that it's cumulative and impairs judgement. Pilots are in general highly motivated and goal oriented. We are also a proud bunch and have this 'can do' attitude. It's very difficult to assess yourself before starting a long duty when you feel somewhat rested and think you're okay to do the job. Many hours into the flight you may however feel totally different.
How to know you're fatigued and unfit to fly? When you experience yourself during the end of a flight totally worn out, slow in thinking, lacking in situational awareness to the point that you are not sure you can safely handle a critical situation.
Imperfect as this is. This is the time to call in fatigued and file an Incident Report. You were at the controls unable to fulfill your duties.
When management disregards the needs and capabilities of human beings for the sake of profit maximization, refering to their lobbied legal limits, let them deal with the consequences. Every sportscar has a gauge depiciting max RPM. Does that mean it's a good idea to continually run the engine at max revs? Should we as pilots pretend to function when we don't?
We have to act with integrity and call in fatigued when we are. Doing this, things will change. Quickly.