The real wages of workers will tend to be high when

When labor productivity is high.

Explanation:

According to neoclassical economic theory, real wages are equal to the marginal product of labor (MLP). The marginal product of labor is the extra output produced by one extra unit of labor (one extra worker).

If the MPL is high, this means that workers are very productive, and therefore, are paid a high real wage accordingly.

This is why countries with high labor productivity like the U. S. or Switzerland also have very high real wages.