Are you referring to the Business personal resource, or to business in general? Broadly, a nation is self-contained so in Dawn there will be the run of medieval professions: farmers, bakers, butchers, brewers, craftspeople of all types, lawyers, merchants, and so on. Very few of these will be Dawnish player characters. I don’t have access to the data but I suspect the Business personal resource is rare in Dawn.
Dawnish citizens, especially the nobles, pursue glory which is (deliberately) a little vaguely defined but is about personal achievements and the fame for those achievements. It can suffer from being too closely identified with battlefield achievments - a battle is a good place to earn glory, it is far from the only one.
The accumulation of wealth is not a glorious act. Many nobles try to publicly distance themselves from the idea that they are interested in money. The Dawn Economic Interests page gives a good discussion on how this works. Broadly, trade in Dawn is something to be avoided by most nobles, or handled discreetly by those who need to get involved. There is no shame in going trading for some Orichalcum if you need to make a Vorpal Sword, but there’s no glory in it so don’t boast about it. There is glory in making a magic sword, and also in how it is used.
I work on the understanding that nobles have someone working for them who handles their financial affairs, and this person may or may not be a player character. Some groups have a seneschal player, and it is that person who handles the house’s business in the field.
Every player character has access to a personal resource which provides them with income of a sort - either in silver Crowns or some kind of rare and precious material. My current character has a Fleet, and I imagine there’s an NPC ship captain who does all the sailing and trading for him, and hands over the money and other resources once a season.
A foreign businessman is likely to find themselves directed to the seneschal by any nobles of the house, especially if “a businessman” is how they identify themselves.