It's ironic, especially when the obvious engineering solution would be to add tracking paint/sigils on the ball... and doubly ironic when the engineering solution would be unlikely to be accepted.
It’s not hard to fix your software that you created. It’s much harder to get global consensus on a change that wasn’t required before your buggy code was released into the wild.
A few companies actually managed to get a production process that put a chip in the ball without affecting flight characteristics (there are a lot of regulations around this), and these balls were used in competition once (Club World Cup 2012).
Ironically, the most complicated bit is the sensors in the posts.
All GLT is Computer Vision based now.