Todd: The logic is not that complex.  If you're wealthy you a) contribute to the campagns of lawmakers, b) either have or belong to associations who have lobbyists to promote your desires, c) have the money to hire the best land use consultants and attorneys to research the regulations and find the appropriate loopholes, and d) have the money to purchase the land and develop it for huge profits.  

If you're middle class/working class and have a modest home in an R1 zoned property you will not be able to develop that "tiny house" project which would a) provide an affordable residence for a tenant and b) help you financially and c) promote the "infill/redevelopment" which the city ostensibly supports.  Your idea might be sensible....but, those "high-roller" projects are "cents"-ible and will be approved.  BTW: In my opinion, the idea you suggest is one of the most reasonable, achieveable suggestions to provide "affordable housing" I've heard.  Good luck on it.  Gary Crum