Just to pick on one player, California prison workers’ union have immense political power. They have many members, and their self-interest is more prisons and more prisoners.
To go further, when you warehouse a bunch of people who can’t vote in a geographical area, you create a situation where few voters get to wield disproportionate power at all levels.
I took a quick look at campaign financing laws in some other countries (UK, Germany, Canada, and Japan) and it seemed that the U.S. was the exception in allowing trade unions and industry associations to give money to politicians, along with unrestricted corporate contributions to political causes.
What would be considered bribery in many other countries is still legal in the U.S.
To go further, when you warehouse a bunch of people who can’t vote in a geographical area, you create a situation where few voters get to wield disproportionate power at all levels.