Finding debris
As stated, the Western Australian coast is sparsely populated and with large sections that are infrequently accessed, if at all.
Increasingly so the farther north you go, as was predicted for any debris from MH370.
As much as we might like to think, the coast is not all white, sandy beaches either.
There are long (read as 100's of km) of high inaccessible cliffs against which debris would likely be beaten to smithereens.
Not to mention long sections of mangrove forest that would simply swallow debris coming its way and into which people seldom enter.
And north of Yampi Sound the coast (read as 1000's of km) is rugged, hostile and general never accessed, certainly not in terms of "going close enough to identify debris".
It is very possible the debris might be found, but it is at least as possible that it might not