As OTWO pointed out, JWs suing "mother" will be a rare thing as it is drummed into their heads that suing "your brother" is unacceptable. If you're conditioned to allow a brother in the hall to cheat you without legal recourse (which happens all the time) then you know that the majority of the R&F wouldn't even consider suing the WTS for damages in any situation.
The lawsuits will have to come from outside. The elderly sister driving in service who shouldn't even be driving period (every congregation has one) who causes an accident with injuries. Is she alone liable, or would the WTS also be liable since, as a church volunteer, she was serving as a spokesman for the church? If the Society has placed barriers to protect them from lawsuits, then the local congregation could be sued, basically bankrupting them out of existence.
If the local congregation and maybe the Society can be held liable in auto accidents caused by publishers, then the way the preaching work is carried out now will have to change.
Before I left, I figured the day of anyone and everyone driving in service was over. I've seen some bad, bad drivers in the JWs, some of the worst. Yet, brothers have no qualms about overloading a bad driver's car with JWs and send them out to the killing preaching fields. I figured that they would have to have an approved list of drivers for field service by now.. There were some people that I refused to ride with because of their bad driving. More than once I caused some hard feelings for my seemingly harsh stance on the subject, but my life and health was more important than their feelings.
When these people cause accidents and the ambulance chasing lawyers realize how much money the WTS has, you're going to see more and more lawsuits.