Countries all the time takes measures at national level, and several times they create disasters. For example, they believe adding or removing a new tax will be positive for the overall economy, and it turns out to be bad and it causes a big problem. Are there examples of countries taking measures at city level, to see if that measure could succeed or fail nation wide? For example, trying how a tax affects economy in a small town first, if it impacts positively, trying it in a city, if it fails, restore the town's economy to its original state (since it is a small town a country with all its resources can fix economical mistakes in a town) and if it goes well scalate the measure, after the town, trying in a city, later in a county or deparment, later in a province or state, to finally reach nation wide. Do countries ever do things like that, is there any example of a country doing such thing?
Yes, there are lots of examples of countries piloting new economic measures before they are rolled out nationwide. A couple of recent examples are of Finland piloting universal basic income and the UK piloting universal credit in 12 local authorities, which was then extended nationwide in a number of stages.