You've got a couple of statements here that belie assumptions that aren't very accurate.
> Business leaders care about creating more outputs to society.
This is untrue. The reason markets work at all is arguably that it's untrue. Business leaders care about generating rewards for themselves. Markets are a mechanism that ensure that it is profitable to create more outputs to society.
This is a really important concept. Amazon doesn't exist because Jeff Bezos is a selfless individual who cares deeply about making sure every American has free next-day shipping. It exists because Jeff Bezos wants to make money, and the market demonstrates that selling products with free next-day shipping is a desire that other people have, and therefore it will be profitable for him to fulfil that need. Markets are about assigning value to desires, and using that value to ensure that goods and services are traded efficiently and flexibly across the whole market without someone needing to coordinate things from the top.
This is (mostly) a good thing - efficient distribution of services across a market is why we like markets and tend to use them a lot across our economy. But we need to be honest about how and why they with, and it's not because business leaders are trying to be selfless to society.
On the other hand,
> Unions work against that goal.
This is also untrue. From a market perspective, unions are a collective bargaining tool used by workers selling their work. In the same way that it's easier for a handful of truck drivers to collect together and form a business, rather than each independently set their own price for their labour, so is it often easier and more efficient for a group of workers to collect together to form a union.
But like with any market, while people can haggle over the best price, the item must be sold at some point in order for all parties to get their rewards. If you've got a melon that you want to sell for $100, but no-one will buy it at that price, then all you'll have at the end of the day is a mouldy melon. Similarly, workers in a union want to sell their labour, because if they don't and the business collapses, they're all out of a job.
In that regard, a union is a tool used by people selling their labour in the market in order to achieve the best price for them (in this regard, they are just like the business owners from before, where the market uses their personal desires to generate value across the whole market).
In fairness, this is a very simple model, and so it doesn't tell the whole story. Markets have failure modes such as monopolies where the simple analysis of market efficiency tends to break down. On the other hand, if a worker cannot sell their labour, then they cannot eat and cannot access housing, which in practice puts a lot more power in the hands of the person buying labour then the person selling it. It's important to remember that the market model is just one tool that we have for managing resources, and in practice most successful countries use a mix of markets and government intervention to provide efficient access to goods and services across the economy while also preventing common failure modes. Rules to protect workers and unions are part of that mix.
But, despite its simplicity, the market model still helps explain the interactions between businesses and workers better than the naive approach that says that unions are bad and want businesses to die, and business owners are good and want to freely distribute value to the economy. I hope this comment demonstrates that a bit.