Apple will start paying $21B in back taxes to Ireland

Because the Bank of England controls the pound and everyone one who works for it are answerable to the electorate in one way or another.

On the other hand a Eurozone member cannot set it's own interest rates, inflation, can't restructure it's own debt, doesn't control it's exchange rates etc. It takes away nearly all the financial tools a country has.

Do you know why you need to bail out Ireland? because it doesn't have access to these tools, It can't restructure it's own debt and it can't control it's own currency and exchange rates to settle it and any changes to the Euro which might be a net positive to Ireland would be global and could often result in a net negative to other Eurozone members like Germany.

Lets take exchange rates for or example.

They have the same exchange rate which means that if Ireland and Germany want to export potatoes they both get paid at the same rate in their local currency.

This is a huge deal because it prevents one country from being more competitive than another as it would lose too much on the exchange rates.

This essentially takes away an important tool that countries have which is being competitive on export by reducing their prices but maintaining a good local revenue through favorable exchange rates.

And while it might appear "fair" it's not because fixed exchange rates favor larger economies like Germany which can be competitive more competitive due to simply their sheer production capacity.

Next you have imports again the exchange rate is fixed, also the import taxes are fixed so importing goods into Ireland would cost as much as to Germany excluding other marginal costs which again is a problem because Germany is a larger market, it's closer to the Netherlands which is the major port into the EU, it's on the mainland which give it easier access to the med as well as a land route to Russia, Turkey and beyond.

Now lets look at another example debt restructuring.

Lets look at both "internal" and "external" debt, in this regard internal means in your own local currency and external means in a foreign currency.

Internal debt you can repay by well simply "printing more money", sure you can't go wild with that but this is something all countries do all the time they play with interest rates and many other levers and reduce their debt at the expense of higher short term inflation.

External debt again if you control the exchange rates and control the supply of your own currency you have much better tools for debt restructuring.

And these are just the most crude and basic examples there are benefits to the Eurozone but you do take away most of not all of the tools countries have of managing their own financial and monetary policy. You also cannot make adjustments that you could make otherwise because you now have to set a unified policy across all member countries.

I think eventually this will lead to the breakup of the Euro... Fixed exchange rates generally don't work long-term without fiscal transfers to balance things out (like the US's federal budget does for the states). I don't think the EU can keep this up for that much longer - at some point they'll either have to consolidate fiscally or break up the monetary union.

According to certain theoretical frameworks... Empirically though there generally isn't any causal relationship demonstrated between corporate tax rates and wages, economic growth, or unemployment in most statistical data.

This is a really big debate in Australia at the moment, a lobby group made up of large corporates (the Business Council of Australia) is campaigning heavily for a tax cut given the recent Trump cuts. So there's been a lot of examination of this data and the best they have is intuitive arguments ("of course if there's more profits you'll have more investment and employment") but they admitted in a Senate enquiry just yesterday that they didn't actually have any demonstrable statistical evidence that tax cuts have caused employment growth, wage growth or increased investment in any developed economy.

Their is no penalty for overpaying your taxes unless you mean the implicit loss of the time value of the money overpaid.

Anyone who's been "penalized" for overpaying their taxes was actually underpaying their taxes prior to their overpayment. People don't realize that taxes are generally due over the course of the year (usually quarterly), not all at once on April 15/16/17. The April deadline is just the due date for the final payment of your prior year's tax liability. If you were underpaying during the year, you could be penalized for that even if you overpaid in April the following year.

This is why trying to game your withholding on your wages (i.e., minimal or underwithholding) is such a bad idea. Any gain (i.e., investing in stocks) is usually more than offset by the penalties and interest you pay if you end up being wrong about how much in taxes you owed. The stock market would have to have a very bullish year to see an upside, usually better than 10% growth--and the target just goes up as interest rates go up.

There's a big difference, Apple was directly told by Irish government these taxes aren't required. Apple is paying extra taxes after it was ruled that Ireland was incorrect. Why should Apple be fined for what Ireland did wrong?

You are required to pay the installments on time all the time, nothing has changed in the last several years related to this.

The analog would be: IRS told you that you didn't have to pay the installment this year but next year instead. A court then said IRS was wrong, you have to pay back taxes. You wouldn't be fined because IRS was wrong this time.