I took it to mean that workers did what was asked and no more — so productivity stayed constant.

Which was contrasted with engaged employees, who sharing in more of the profits, have an incentive to increase productivity — eg, by inventing a tooling improvement for the assembly line.

I think the overall point was employers are “penny wise, pound foolish” in that small productivity “gains” caused employees to disengage which is causing long-term slowdowns in improvements — improvements typically driven by employees stepping up and doing more.