it's a bit different, voting for a Democrat president is excluding the Republican one. When you vote for an union, you absolutely do not vote for your employer

it's a bit different, voting for a Democrat president is excluding the Republican one. When you vote for an union, you absolutely do not vote for your employer to become an asshole, it's not "either the union make the employer improve employees work OR the employer does it on its own". The union and the employer could create an alliance to make life better for the employees. Look at what police unions and conservative towns have done, unionized policemen can literally get away with murder. There is no exclusive choice as to who should plan bathrooms breaks for runners and drivers: either the employer, or the union, as long as people stop having to pee in a bottle, you could even have a coalition with a giant conspiracy to have employee go to the bathroom when they need to.