Over the years, Thanissaro Bhikkhu has cleared up a lot of misunderstanding about what metta – and its companion mindstates – is and is not.
The brahmavihāras, or sublime attitudes, are attitudes of goodwill, compassion, empathetic joy, and equanimity that you spread to all beings, without limit: in other words, with no limit to the amount of goodwill, etc., that you spread, and no limit on the number of beings to whom you spread it. Each of these attitudes is an antidote for mental states that can get in the way of training the mind.
• Goodwill, a wish that beings will be happy, is an antidote for ill will, the desire to see beings suffer.
• Compassion, a wish that those who are suffering will be freed from their suffering, is an antidote to cruelty, the desire to actually harm others when they’re in a position to be harmed.
• Empathetic joy, a wish that those who are already happy will continue to be happy, is an antidote to resentment.
• Equanimity, the ability to maintain the mind on an even keel when events don’t fall in line with your goodwill, is an antidote to irritation.
These attitudes boil down to two—goodwill and equanimity—in that compassion and empathetic joy are basically extensions of goodwill. Compassion is what goodwill feels when encountering suffering; empathetic joy is what goodwill feels when encountering those who are already happy. The Buddha may have separated them out from goodwill in his list of the brahmavihāras because they’re good checks for the honesty of your goodwill. If people whose behavior you don’t like are suffering the consequences of that behavior, is your goodwill sincere enough to want to see their suffering end? If people whose behavior you don’t like are enjoying the fruits of past good actions, can you honestly say that you’re happy for their good fortune?
Equanimity is the backup for cases where, for the time being at least, there’s nothing you can do to stop people from suffering or creating the causes of suffering. https://www.dhammatalks.org/books/Undaunted/Section0010.html#sigil_toc_id_8
We’ll consider these things more deeply, but for today it’s important to understand that we are not wishing for anyone to change specific behaviors. Instead we give the blessing of hoping that all beings learn to free themselves from the things that oppress them. We can’t free anyone else, but we can try to free ourselves, and we can wish that everyone, everywhere also makes that effort. It is all possible, and we can’t make it happen for anyone else, but we can model the change.
“May these beings be free from animosity, free from oppression, free from trouble, and may they look after themselves with ease!”— MN 41
The Buddha's Advice to Laypeople 
An important point ~ made, I think, too seldom, but ably put here: we need to focus control ultimately on the feelings behind our actions. When those are addressed and brought into balance action follows, as you’ve pointed out, easily. 😊
Love the final paragraph especially. We can’t free anyone else but we are responsible for liberating ourselves. May we be free.