Management leave toxic managers in place on purpose. Financial success, getting things done, being too expensive to fire, company culture or not being toxic enough are all excuses to keep toxic managers. They know the costs to their organisation, and they know the suffering of their employees, but they sacrifice them by taking no action.
I find this disturbing in itself, but worse, they never help subordinates work with toxic managers. They leave subordinates to discover ways to cope with toxicity on their own, through books and articles. If they helped, they would have to admit they have a policy of keeping toxic managers in their organisation. I have never seen any organisation do that either. The only time management admits to keeping toxic managers is when they help coach a few high-potential toxic ones to become non-toxic.
If senior management don’t know they have toxic managers in their organisation, they should know. It is part of their job. They should have processes in place to detect managers who are a danger to the organisation. Many HR systems detect incompetent managers, but there are few to detect toxic ones. ‘360 Feedback’ is one such system, but even here, I have found that when a toxic manager is discovered, management does nothing.
But there are organisations out there that never accept toxic managers, on principle. They have systems to detect them and then take action, either by firing them or coaching them to eradicate their toxicity. These are the organisations to work in.