There's a difference in attitude and process to photographing people compared to photographing landscapes. But there are similarities too. As much as we say that people are unpredictable and that we don't know the outcome of the interaction, the same can be said of landscapes too. We tend to think that landscapes are static, unchanging, but I've had my fair share of unpredictable weather conditions and many images that have 'got away from me' for reasons I had no control over - usually weather / light related.
But I think making images of people is very similar to making images of landscapes from an asthetic point of view. Take the picture of the old lady above. I think I was attracted to the image of her because of the complimentary colours. I'm sure that this attraction is similar when making photographs of landscapes - we're not simply attracted by the compositional aspects or the subject matter alone: we're attracted by the bringing together of colour, shape, form, light. Many aspects which I feel are the same for people images.