Another Fixed Rate Inconsistency?

Why do those people who agitate for a fixed exchange rate between currencies also advocate for a floating rate between government bonds and the currency?

If a move between bonds and currency needs to be discouraged by a floating rate, then why doesn’t a move between a local currency and a foreign currency need to be discouraged by a floating rate?

If the Euro is such a great idea across such a wide area, why aren’t Eurozone government bonds payable at par on demand at any bank in the Eurozone?

After all they are just unspent savings.