I think that Jade does not want to go anywhere with Amber for 2 reasons. The first one is that she does not want to bring attention to her and Amber and have people taking pictures. The second reason, and I think the more important one, is that Amber is not that mobile and tires very quickly. So, Amber is slow and needs to rest quite often while walking. Jade, being athletic, is far more mobile and find it difficult to walk with her. This is why the only time they are out is when Jade is driving with Amber.