Have you noticed something? Trade Unions very rarely call their members out on strike over pay any longer. Nowadays it is on 'safety' issues. Usually spurious ones. This now seems de rigeur for the RMT whose strike today is ostensibly on the safety consequences, and the Fire Brigades Union also cites safety as one of the reasons for their strike. This is an interesting development because the issues are almost unresolvable. The unions in these sectors can cite any changes in working patterns as damaging to safety and the employers deny it. The trouble is, neither can prove it one way or the other.
Of course the unions never mention that company directors can be criminally liable if they introduce measures which compromise safety. That's a pretty powerful disincentive to do so.