I feel the flow of this writing is rambling. Is the underlined trying to say that the consumption of travel services can change depending on how rich you are? If you are wealthy, you will travel by air, and if not, you will travel on foot? Is it the gist? I can't get the unified theme of this passage.
st19)As a form of mobility, travel is an integral component of the human experience. There are a number of different conceptions of travel used in the leisure and recreation fields, with the concept changing over time. Since 1990, the concept of travel has become increasingly important in sociology and human geography. Different levels of mobility have led to distinct cultures of travel consumption. It is also recognized that, because of communication technology, it is possible to have access to different cultures and landscapes without requiring physical mobility. Instead, virtual mobility and travel is growing in importance both as a form of recreational activity and as a means of promotion by places seeking to attract visitors. Nevertheless, the consumption of travel services cannot be separated from the social and economic relations which they are embedded.