Final answer:
The share of U.S. workers whose wages are determined by union bargaining is lower compared to most high-income countries due to generally lower union membership and less influence of union negotiations on nonunion employee wages.
Step-by-step explanation:
Compared with the share of workers in most other high-income countries, the share of U.S. workers whose wages are determined by union bargaining is lower. This is because, even though the percentage of workers belonging to a union may be similar in some cases, union membership rates in the United States are generally lower. In contrast, in countries like France and Spain, union negotiations often determine pay even for nonunion employees, which is not commonly the case in the U.S. Therefore, in terms of union influence on wage determination, the U.S. ranks significantly lower.
Unions can affect wages because they act as the sole supplier of labor for their members and can negotiate collectively for higher wages. However, this often leads to employers hiring a smaller number of workers at these higher wages. Conversely, declining union membership has implications for collective bargaining power and may result in slower wage growth for union workers.