Why aren't unions doing better?

NPR -  Just 10% of American workers belonged to a union in 2022, the lowest in Labor Department records going back to 1983, when the rate was 20%. Never mind that 71% of Americans approve of unions, the highest in nearly six decades and up from 48% in 2009, a Gallup poll conducted last summer found.  The bottom line is that labor law itself is tilted in favor of employers, say researchers who study labor movements, often making corporate hostility toward unions too hard to overcome. The recent groundswell of public support is far from enough to spark a union comeback.