"I'd hate to get hauled in for charges of whatever if a traffic camera caught me flipping off some arsehole who endangers my life and that of my grandson by some irresponsible manoeuvre on their part"

That surely is a bit of a bad comarison and wouldn't be at all comparable with what she did though? She was abusing completely innocent passengers simply because of who they were - not because of anything they had done to endanger her life etc.