But i thought we now have COAST GUARDS - Army cannot be involved in basic civilian duties like those.
I agree about the army's role. But these folks probably just lack the resources to get them from down there. But this is not the US Coast Guard. They need to
a) locate the vehicle then
b) get well trained divers with all the right equipment to function down there.
a) would require equipment that can ping and locate the car against the background. This may or may not be straightforward.
It seems easy when you watch movies. But a lot of these movies are in a locale with a much much more impressive array of resources. And even in these places, it's not that easy in real life.