Getting into an orbit next to some other small object is kind of hard. In the GIF you can see Hayabusa-2 making multiple orbits below the asteroid's orbit to catch up (lower orbits are faster) before it raises its orbit to the height of the asteroid. Once it reached the asteroid it had to do another correction to the orbit to make sure they stay together.
In comparison, meeting something massive like a planet is very single: go into any orbit that nearly hits the planet, and when you are there slow down enough to let charit gravity pull you into an orbit around that planet.
tl;dr: more gravity makes rondevous easier and quicker
In comparison, meeting something massive like a planet is very single: go into any orbit that nearly hits the planet, and when you are there slow down enough to let charit gravity pull you into an orbit around that planet.
tl;dr: more gravity makes rondevous easier and quicker