Yes, it's basically a computer/supercalculator in the rocket...
Well, for the cost, their are really effective, and also, their are used to hit a concentration of troops mainly, or a big wide position. There's also a moral effect since you never fire those rocket alone, you will always fire a volley with at least an entire battery. So imagine, a few dozen or hundred rocket hit your position, and rocket sometime have more payload than an artillery shell, so it's devasting... To give you some fact, the CPE (circular propable error) of an artillery rocket is around 5m-40m depending on the model, it's not accurate. Well, it's sad to say, but weapon and military equipement was not designed to be convenient with the civilian, they are conceived to kill and be the most efficient possible... yes, if there's a civilian in the sector, he could be hit too...To give you some idea, a 40-tube 122mm rockets BM-21 (Russian) truck can easily bombard the equivalent of area of 2 soccer field with 1 volley of 40 rockets... And normally, a russian rocket battalion is made of 18 truck, that mean each volley will be of 720 rocket... Normally, NATO's combat doctrine don't use those rockets in urban warfare and in any situation were you need poinpoint support, because it destroy the entire area... It's very effective...