I wonder if there are categories of people that respond in similar ways when they are in the same category, but the response would vary from one category to another. For example, people with low blood pressure would not benefit from a low sodium diet. Yet we are all told "reduce your salt intake".
Two phase power is very, very rare. You are probably thinking of split phase power which is a form of single phase power. It is ubiquitous in American residential power. It takes the form of two hots at 240VAC with a neutral between them, allowing you to get 120VAC from the neutral and either hot.
Microcells are good for carrying lots of traffic from lots of mobile stations. In rural areas, coverage at the lowest cost per square mile is more important. Also, farmers aren't always near the highway, so microcells on the highway would not work well for them.