Tandem Minecarts

In light of the latest snapshots for Minecraft: Java Edition (1.21) adding experimental improvements and testing new functionality for the minecart item, a thought had occurred to me:

Two entities can simultaneously ride in a boat, a feature that opens countless doors for traversal and the transportation of players, mobs, and items alike. Why not give the minecart the same treatment?

Boats are an excellent means of crossing water, and their capacity of two makes them even more essential for long-distance transportation. To increase the capacity of minecarts (or, alternatively, to add a separate, larger variant with a greater carrying capacity) would hugely benefit the practicality of traveling on land in a minecart. Imagine riding a rollercoaster right behind your best buddy, carpooling down your Realm's community highway, or even keeping a close eye on your animal friends as you escort them to their new home!

As of Minecraft version 1.19, a boat can contain a chest, with an additional capacity of one player or mob. As early as Minecraft: Java Edition's alpha versions, minecarts could contain chests, and have since been granted the ability to also carry furnaces, hoppers, TNT, and even command blocks. However, the aforementioned minecart variants cannot be ridden by the player, making their contents more difficult to supervise and control the movement of.

To increase the carrying capacity of the minecart would help to make them function as conveniently on land as boats do at sea!