I think the rafts you're looking at are just gear rigs, on long multi-day trips usually there is only one person with a set of oars. The boats have frames and lots of cargo space for food, clothes, toilets, tents, kitchen, etc.
Depending on the size of the boat and the difficulty of the river you can have more people on them, but still only one person rows.
Depending on the size of the boat and the difficulty of the river you can have more people on them, but still only one person rows.