Does the union actually do much for them? I know in a lot of blue collar work unions are actually serious, and can do strikes and stop a business in it's tracks

Does the union actually do much for them? I know in a lot of blue collar work unions are actually serious, and can do strikes and stop a business in it's tracks if the workers feel they are being mistreated. Why does that not happen with doctors? I've not heard about it happening, anyway.