How big is the income gap between rural vs. urban in wealthy vs poor nations

My impression in the US is that despite real estate being far higher in urban areas of the US, wages are not much higher. Maybe 20% or so, but working in a small town or a town with under 100k people will still earn you a fairly comparable wage largely irrelevant of whether you are skilled or unskilled, educated or not. People at McDonalds do not make $17/hr in Manhattan, as far as I know vs the $7.50 you see in a smaller town.

But it appears that in poorer nations the gap is huge, with wages being 2-3x higher.

I would assume this is because in the west we are a service/information economy and in poor and middle income nations they are more manufacturing based.

But I get the impression that even service sector jobs in developing nations pay far better in urban areas than rural areas.

Then again I grew up in a small town and I remember a conversation some cops were having at a table near me, where one said he earned under 26k a year and barely missed the cutoff for welfare for his family and I believe cops in larger cities earn closer to 60-80k. But in some ways you’d expect public service sector workers to experience a massive wage gap since people do not pay as much in property and local taxes in rural areas.

So is there a massive wage gap for public vs private sector workers in urban vs rural areas (teacher, firefighter, police officers)?

Is there a wage gap for private sector workers? Does it depend on the skill level, education level, or field?

Does is vary massively by national income (wealthy, middle income, poor) or do some poor nations have a minor income gap between urban/rural while some wealthy nations have a huge income gap?