I have noticed that a ship appears by the boardwalk and let's off passengers when I finish up the boardwalk items and pop the balloons. These seem to be the citizens that walk around the city and give coins and items. Then when it's time to do the boardwalk items they are gone again.
Update
The Community Manager has feedback to the team and they've changed it a bit so that the citizen should be coming in a bit more. Hope you see the changes!