In a country like Singapore where the vehicles are so expensive, most couriers use bikes to deliver any small items that can be fitted on them / inside the bike’s box and only use vans or cars for bulky and more expensive delivery services.
This means that if you were to deliver documents or a small gift / parcel, most courier services in Singapore will be using a bike rider to deliver your items instead. This will be more economical for them, and will also be cheaper for you.
Most van courier in Singapore actually deal with bulky items such as corporate printers, lots of parcels and gifts, and basically odd shaped objects. Paper and documents and cheques would almost always be transported and couriered by a biker instead.
Whenever you see a van courier, he or she would almost definitely be stocking lots of parcels at the back of his or her van. Usually, they deal with mass pick ups and deliveries. This means that they will be going to a few locations to pick up lots of items, storing it at the back of their vans, and then delivering to many locations islandwide over the next few days. Most courier driving vans deal not with same day deliveries, but instead deliveries over one to two working days most often. It is often motorbike couriers who deliver and perform same day deliveries because they do not have much storage space in their boot anyway.
Most van delivery companies deal with items which are smaller than small furniture. After a certain size, it would require a lorry to actually fit the items in it.