It's not as simple as you're making out. In a textbook situation, yes, it is basic geometry. But there are so many variables. Using some technology to superimpose digital lines on the pitch could be done, but that's no help when players can pass foward relative to the pitch due to them imparting their own forward velocity onto the ball

Apart from the fact that one decision is based on the absolute position of the players and the ball and the other is based on the relative position of the players and the ball, you are right, they are exactly the same

Good quality ones are. They use them in geology to measure land movement of millimetres over long periods of time.

No I said the system you proposed wouldnt be possible. To avoid confusion i mentioned Hawkeye the company, not hawkeye the system.

Even for you Smokey, that's a poor attempt to wriggle out of something you've said!

Its not really complex to say there may be an engineering solution for accurate judgement of forward passes, but your's wasnt it.