There is a /setting to change the /rpv behaviour. Type '/set rpv' to quickly get to that setting.
The first option is default. If you have a primary active vehicle, it will return it, no questions asked. If you have a secondary active vehicle, it will become the primary.
The second option is an inverse of the first - if you have a secondary vehicle, it will return that one first. If you only have a primary, it will return that instead.
The third option will return a primary active vehicle only if you don't have a secondary. If you have multiple active personal vehicles, it will prompt you to select which one to return.
The fourth option will always show the selection menu, even if you only have a single active vehicle.
Shortcodes were added because people can have like 100+ vehicles which can take a long time to find in menus. There's no need for it when there are only two vehicles to choose from..
This is not something I feel is needed.