The rules are hard to apply, Klaus. Just think about two parts of offisde.
1) the offside decision point for a player receiving a pass is his position relative to the two deepest opponents when the ball is passed. we are so used to the Sky Sports talking heads pausing the image as the ball is passed, overlaying an offside line, and then discussing whether it was offside or not. in real life, when that ball is released, a linesman needs to look down towards where the ball is going, identify the potential recipient(s), find the last two opponents, and make a decision with all this information processed in under 0,1 seconds. of course he's going to get a few wrong. and it's not about incompetence. it's just nature. this is where technology can help. give the linesmen in real time the same perspectives we have.
2) the offside player interfering with play. it feels like officials almost always get this one wrong. players are standing still in front of goalies and not interfering, etc. having a second look, often wouldn't hurt. again, as an official, there's tons of ?"information you're processing, while you're also wondering "what's this motherfucker doing playing statue in an offside position
by the way, i'm a fan of the former. the latter sounds good in principle but is more open to abuse.