Legalese
The bid system is not fair but it is not discriminatory.
Any new system of work allocation would have to take into account any negative impact on those with family.
So there are both negative and positive discrimination issues to be considered.
Considering those with children and other family commitments(in LH) any change to the seniority or bid system would provide little if any improvement for those who are close to the bottom.
Those who are sceptical of these points I suggest you contact your nearest barrister/solicitor for an infomed opinion.
I have done so and had these points veified.