Importance of payment

What is the importance of paying the settlers? What can they do with that money? It would be useful to have a market where they buy goods to produce or survive, it would give more life to the game, when having a home of your own it would be good to have a tax.

for now it’s just a “reward” that some colonists want to be happy there is no really use for them, coins are only usefull for you and the trader.