RPGs are perfectly reliable as long as the warhead collides with something solid, like a tank or concrete. They are not anti-personnel weapons, they aren't meant to be shot at people. People are soft and mushy.
Nobody knows about the anti-personel rockets, they don't appear in movies and aren't used much because they're just oversized, self-propelled hand grenades. They're basically redundant because the extra range generally isn't a bonus over hand-grenades or launched grenades.
The PG-7VL rocket is a HEAT (High-explosive Anti-Tank) rocket with a shaped charge in the nose, it's basically a copper cone with explosive behind it to direct and concentrate the blast into a relatively small area of the armor, which would do more damage than an undirected explosion. You see these whenever you see an RPG-7, basically.
The OG-7VL rocket is a big pencil-shaped fragmentation rocket (I imagine those grooves allow the case to fragment easily), it's just a big self-propelled frag grenade.
(Glorious information from stalker.wikia.com)
P.s: hitting a target with an RPG(-7)'s rocket is difficult beyond 300m because they're 'dumb' warheads without any tracking, in the Afghanistan war, folk with RPG-7s would engage targets at under 100m, as it was much easier to ensure a hit. The newest issue RPG models in Russia have IR/Laser tracking, which rules out "the closer the better" as a strategy.
