The fact that we live in a capitalistic society means that money makes things happen.
It is an indication of resources. It can be used to represent and signal goodwill. It can be used to simply allocate. There is nothing inherently amoral about money. That is why it's appropriate to use it for charity, to use money as a tool to improve the world.
Conversely, money is not the only neccessary tool to deploy. Just because it is amoral doesn't mean that you must only use money to achieve your goals.
You must also consider the social and emotional factors when negotiating with people. This is a pre-requisite that is uncontroversial. Ultimately, you are always dealing with people - not the mechanisms of one aspect of society.
That society is largely organised under capitalism does not define it as a moral authority. Thus, there must be some other moral and etiquette. It does not justify using money alone and reducing people.
After all, capitalism is not universe-defining, it is only very limited in definition: the allocation of (some) resources through markets.