But they'd get accused of colonialism if they actually tried to help directly like that (and perhaps it would be true). So they're left in the untenable position of dealing with mass migration or funding warlords.
Not all of them make it. The vessels aren't particularly seaworthy, and they're not allowed to dock, so effectively they dump their passengers in open boats and rely on the coastguard rescuing them and taking them to Italian soil.
Russia used SC veto 7 times just in last 3 years. The last time USA has blocked any resolution was 2011.
TL;DR: Regime in cambodia genocides about 1/4 of its population between 1975-79, is removed from power by Vietnam. UN helps recovery from destruction of society by previous govt & transition to new govt which after some initial chaos stabilizes. It's still not a proper democracy, but at least it isn't genocidal.
Considering the extremely difficult circumstances (a genocide so bad that it destabilized society & vietnam being an authoritarian regime), I am actually impressed by what the UN managed to pull off.