Roads are a lot more flexible though. Tractors also use roads for example. As to bicycles and pedestrians.
Note that the above is about very rural areas where seeing 4 of the above per hour on any stretch is busy. As you start scaling up density it makes sense to separate uses, and trains quickly become the best option for various reasons.
Roads go everywhere you want to go, and it’s worth sending a truck for a much smaller load than a train
Roads go anywhere you build them.
Rails go anywhere you build them.
Roads are a lot more flexible though. Tractors also use roads for example. As to bicycles and pedestrians.
Note that the above is about very rural areas where seeing 4 of the above per hour on any stretch is busy. As you start scaling up density it makes sense to separate uses, and trains quickly become the best option for various reasons.