I'm with Piper on this issue. If you have nothing to hide you have nothing to fear (though if CASA Avmed can be kept out of the process, there would be less to fear). What's wrong with seeing a GP every couple or so years to run a basic assessment and issue a piece of paper to insert in your licence?
Seeing a GP occasionally may even identify an issue that could ultimately prolong your life.
I would also be quite comfortable with all road users having to do a basic medical for intitial issue of a drivers licence and another medical examination at some later stage in life. Where I live we don't even do an eyesight test at age 80, which is all in the name of 'no age discrimination'. I am rapidly approaching that age, and right now my eyesight is borderline Class 2 medical standard, which means it's also marginal for driving, so I am getting it fixed at considerable expense. Many drivers don't, because the law does not mandate a test, and so put others at risk every time they are on the road.
Same with some pilots - if they are not compelled to do something, they'll go into denial mode. With these types the whole 'self assessment' thing is a crock.
The first time some fat fool concealing or unknowingly having a medical condition carks it in flight and takes his grandkids out with him, or plows into the local school, CASA will scrap this and serve up something we really won't like.