the point most people seem to be missing is, that in tennis, rugby, cricket etc. the game has a natural stoppage in which to check the video.
Say for example that the ball didn't cross the line yesterday, and germany launch a counter-attack and are four on two with our defence, should the ref stop play to check the vid, and germany lose their chance? what if in the counter attack a german player gets brought down and does his cruciate ligament, the ref then goes back to check the video, and it is a goal.... the ref can't undo the injury.
i personally would prefer technology, but it doesn't fit the nature of the game. And if you accept that refs are only human, their errors should balance out at the end of the day.