Why doesn’t everybody leave? The border may be quite porous as many long borders are, but people still have to get to it. The Waterfords seemed to have travelled a long way just to get to the meeting point and it didn’t look like a densely populated area. I can’t see an Econofamily or Martha having the resources to get within walking distance of a border.
June’s decision to not help Mrs Lawrence. I think she was in a difficult situation. Her first instinct seemed to be to get help, but if she’d done that and Eleanor was brought to a hospital, then even if they’d managed to save her, it would have brought unwelcome attention to the Lawrence household. There’s no guarantee that Eleanor would have been fit to travel within the week - even assuming that she would have been allowed leave and not charged with attempted suicide.
And if they did manage to explain it away as an accident, they still have the risk that Eleanor will tell about the plan.
On the other hand, there’s the risk that Joseph won’t want to leave without her by his side, but as long as he doesn’t stop the others going, that’s not as big a problem.
Like I said, I don’t think it was an easy decision for June, but I can see why she let Eleanor go. Now if she’d helped her on her way, that would have been a different matter.