This is a genuinely contested question in economics and policy, with legitimate evidence and arguments on multiple sides. Let me lay out the main considerations rather than pushing a single verdict.
Arguments that unions benefit workers
•Wage premium: Unionized workers generally earn more than comparable non-union workers, and union contracts often come with better health insurance, pensions, and job protections.
•Reducing inequality: As union membership has declined in the U.S. since the 1970s, many economists point to that decline as one factor contributing to wage stagnation and rising income inequality, since unions historically compressed wage differences and gave lower-wage workers more bargaining power.
•Voice and protections: Unions give workers a collective mechanism to negotiate over safety, scheduling, grievance procedures, and job security, rather than relying solely on individual bargaining power.
•Spillover effects: Some research suggests unionization in a sector can raise standards even at non-union firms (through threat effects or industry norms).
Arguments against, or highlighting costs
•Labor cost and competitiveness: Higher union wages and benefits raise labor costs, which critics argue can reduce firm profitability, slow job growth, or push production/investment elsewhere (offshoring, automation).
•Rigidity: Union rules (seniority systems, work rules, difficulty in layoffs/restructuring) can reduce firm flexibility, potentially hurting productivity or the ability to adapt to economic shocks.
•Insider-outsider effects: Some economists argue unions primarily benefit existing "insider" members at the expense of outsiders — e.g., higher wages for union workers could mean fewer jobs are created overall, disproportionately hurting job seekers, especially younger or less-experienced workers.
•Public sector concerns: In government employment, critics argue unions can drive up costs to taxpayers and make it harder to reform inefficient practices (e.g., in some public education debates).
Nuance/mixed findings in economic research
•Effects vary a lot by country, sector, and union structure. Countries with centralized, sector-wide bargaining (e.g., Germany, Nordic countries) tend to show different (often more positive-sum) outcomes than the more adversarial, firm-level bargaining common in the U.S.
•Impact on overall employment and productivity is empirically mixed — some studies find neutral or even positive productivity effects (reduced turnover, better morale), others find negative effects on firm-level investment or expansion.
•The effect on the broader economy (not just union workers) depends heavily on whether you weigh short-term wage/cost effects vs. longer-term effects on inequality, consumer demand, and political economy (e.g., unions' historical role in expanding labor protections and social insurance for all workers, not just members).
Bottom line: Whether unions are "good" depends on what outcome you prioritize (wages for members vs. overall employment vs. firm competitiveness vs. inequality) and the institutional context (bargaining structure, country, sector). Reasonable economists disagree, and the empirical evidence supports different conclusions depending on framing and metrics used. If you want, I can dig into specific evidence — e.g., recent U.S. wage-premium data, cross-country comparisons, or debates around a particular industry — happy to search for more specifics if that would help.