The joker is there purely for television reasons.
The speedway world cup is there for purely television reasons....this competition was dead and buried before BSI came along a resurrected it...so it's their competiton threfore they can make any rules they wish.
If you don't like it don't watch it!!!!!!
In 10 years time when sky have got fed up of the constant bitching from the old gits on this forum what you going to do then bitch about the lack of speedway on tv.