If the board is solely elected by shareholders, whose interests do you expect them to prioritise?

In some EU countries, they put union/employee reps on corporate boards. Generally done by having two boards - a supervisory board containing union/employee reps, which in turn appoints a management board without them. The CEO reports to the management board which in turn reports to the supervisory board

But it doesn’t necessarily stop scandals/mismanagement/corruption - Volkswagen has a supervisory board with employer/union reps, but that didn’t stop Dieselgate. Would employee/union reps on Boeing’s board have stopped the 737 MAX debacle? Hard to know