The requirements are simply stated, and the supporting material in MB handbooks are not the requirments. From the Manual Boy Scout Requirements, 2008, p 116 "Hiking MB"
1 Is the usual first aid requirements
2 is the usual question regarding goor hiking practices
3 "Explain how hiking is an aerobic activity. Develop a plan for conditioning yourself for 10-mile hikes, and describe how you will increase your fitness for longer hikes.
4 Make a written plan for a 10-mile hike, include map routes, a clothing and equipment list, and a list of items for a trail lunch.
5 Take five hikes, each on a different day, and each of 10 continuous miles. Prepare a hike plan for each hike.
6 Take a hike of 20 continuous miles in one day following a hike plan you have prepared.
7 After each of the hikes (or during each hike if on one continuous "trek") in requirements 5 & 6, write a short report of your experience. Give dates and descriptions of routes covered, the weather, and interesting things you saw. Share this report with your merit badge counselor."
Guess what! There is no requirement that the hikes have to be urban, suburbal, wilderness, country, or anything else. The requirements simply state that the hikes have to be of a particular length, and have to have a plan, and a journal. Nothing else is required. Remember the mantra that all are taught when being instructed to be a merit badge counselor (or SM when talking about advancement): "Nothing less nothing more."
Again, it is up the to the MB counselor, when discussing the intent of the scout BEFORE the hike takes place, if a walk-a-thon is acceptable. If you are uncomfortable with the broad scope of the requirements, then I suggest that you write to your Council Advancement Committee your suggestions for change with the request that they endorse them and send them up the chain to the National Committee.
50 year+ scouter -- have held almost all adult leader positions in Cubs, Scouts, & Venturing, currently serving as Council Scouting for Youth with Disabilities Chair.