It is common sense. People tend to try to live where it is most beneficial to them.
The chief cause of global urbanization is the new economic opportunities it brings to people, especially those in the lower income brackets. More jobs = more opportunities. This urbanization accelerates over time, casing other issues. Rapid housing construction leads to overcrowding and slums, which experience major problems such as poverty, unemployment and high crime rates. Additionally, strains on important resources, such as housing and land, leads to higher prices, thus driving the cost of living up in those areas.
This urbanization then leads to urban sprawl, which is where the ones able to do so move to the suburbs just outside the cities, because it is cheaper to live there, less crime etc. Over time these areas begin to become crowded, prices for land, houses etc start to rise, which leads to even higher costs of living. It is a neverending cycle, and is why you have a rather larger discrepancy in the cost of living across the country between urban and rural areas.
By trying to have similar wages everywhere, it would discourage urbanization, and encourage more people living in more rural areas.
And all of that is completely unrelated to a tiered minimum wage. As I've already said it is much easier to live on $12.50 in rural Oregon than on $14.75 in Portland. There are tons of costs you incur in an urban area that you simply don't outside the city. Trying to have similar wages everywhere will do absolutely nothing to combat the cycle you mention. Because there are 100s of other reasons to live inside the big city than a higher minimum wage. All you've done is described a process, you haven't show anything on how a tiered minimum wage contributes to it.
Oregon is miles ahead of every other state in terms of paying their workers a fair wage. Highest minimum wage in the country.
You simply will never see a tiered system in regards to a federal min wage. We are already seeing backlash in several GOP states. Many of them have passed state laws making it illegal for municipalities or counties to enact higher minimum wages in their own areas, or are in the process of doing so.
And yes, there are "tons of costs you incur in an urban area that you simply don't outside the city". And one of the major factors is the discrepancy in wages between the two areas. lol
And prior to 2008 no one would have thought Massachusetts' health care system would have worked for the entire country. Now we have the ACA. There is a reason why they call the states "laboratories of democracy." If it works out well at the state level in Oregon the rest of the country will take notice.
They need to see themselves as, well the old Brittonic word is Combrogi, or the Welsh Cymry, basically "Countryman/Compatriots." I shudder sometimes at the lack of patriotic loyalty to ones own countryfolk, be they poor or out.
*Shrugs* I'm a romantic, I like Sanders vision for the country more than others.
On MMO-C we learn that Anti-Fascism is locking arms with corporations, the State Department and agreeing with the CIA, But opposing the CIA and corporate America, and thinking Jews have a right to buy land and can expect tenants to pay rent THAT is ultra-Fash Nazism. Bellingcat is an MI6/CIA cut out. Clyburn Truther.