[ 6/3/20 ]
Seems to be several major aspects to the answer, in so far as the question is actually accurate in its assertions.
Human biology is complex, and we are very long lived. Multi-generational human trials take a very long time. So it is very difficult to gain reasonable confidence about long term consequences of actions.
Use of laboratory animals as models is problematic for a host of reasons, not least of all the long telomeres of many strains of laboratory bred animals (particularly mice), which makes them very poor indicators of long term effects.
All bureaucratic systems have a tendency to look out for the needs of the system more than the people they effect. This is as true of the many levels of the medical system as any other.
As noted by Josh Camp the economic incentives are not to cure problems, but to optimise the profit available from any particular opportunity (health issue for someone).
Perfect health, and indefinite longevity seem to be technologically possible, but not within a market based system of values. Both would necessitate some very high tech interventions, and some serious social and cultural changes.
There are just too many perverse incentives in the current system, at too many different levels. It is difficult to believe anything coming out of any institution (including any media system) at present.