As pilots we should report to our GPs if fatigued and tell crewing/rostering the real reason for our time off sick. Only then will the full extent of the problem be fully realised so that something can be done about it. What we need is a level playing field for FTLs which should reflect a realistic approach to avoiding fatigue. If all companies had to comply with more rigorous rules, no one particular operator would be disadvantaged. Ok, so the customer would have to pay a little more for the ticket, but if they knew now how knackered we get then I'm sure they'd be happy to pay to have an alert crew up front.
This is the professional, responsible way. At present, people go sick with flu, back aches etc, and the problem is being hidden.