Both of these are directly related to the strike, so I can most definately see the logic in handling them as collective issues.
It appears that BA see the same 'logic' - however an individual has a right to raise a grievance and there is a process in place for them to do so.
As for tying up BA in paperwork - my understanding of the law and the taking of BA to any industrial tribunal (for withholding pay for example) - the individual has to raise a grievance with their employer and the company grievance process has to be exhausted before anybody can take BA to an employment tribunal - that is why so many individual grievances have been filed.