Because there has never ever been a requirement or training for a VFR pilot using alerted see and avoid with another aircraft to remain so far apart that a RA does not take place.
CASA has not seen a requirement for that.
But there
was a requirement to remain clear of IFR routes was there not? Something the Tobago pilot clearly didn't do, at least not with his brain engaged. 1 in 60 rule anyone?
That is why there was a TCAS RA event.
Why didn't the Tobago pilot pipe up and say something? He thought they were going to be clear? He thought bloody well wrong. And that's why it was a whole crock.