Time. Lots of time. And patience.
It appears they are housed outdoors which makes it much more difficult - simply because it is hard to give them enough time to get to know you.
Indoors (which is the only way I've housed rabbits), I open their cage door and set up a pen around that opening so I can sit there too. I sit on the floor with them and they can come out if and when they are ready. Gradually their curiousity take over and they get closer. I ignore them so they don't feel threatened. if I were to try to pet them, they'd just run off and think I'm scary. So I give them time and let them get used to me. This step can take days or weeks -- depending on the rabbits. And it should be daily and for as long as possible.
In time, I can start petting them. I'll be getting to know their body language at the same time -- what do they do when they are ready to be pet (eg. head down as request for grooming)?
It takes persistence and time.