From accounting point of view, debt always equal to credit. A's debt is B's credit, if both A and B have credit (saving), then there must be some one in larger debt to balance. American government's debt could be balanced by surplus countries' credit.
How do you reconcile this within the Bitcoin economy? Do people with Bitcoin savings owe a 'debt' to some other party?
Or can such savings be viewed as loan with zero interest and no maturity? Which is the definition of money.
No. Bitcoin is not debt. Dollars really aren't either, but the idea persists. Once upon a time, federal reserve notes could be traded for the equivalent value of gold, so the dollar was a debt that the government owed to the bearer. Those days are long gone, so now dollars aren't really debt any more, since there is nothing that you can redeem it for, except another dollar.
So why do we have to pay taxes if the govt can create as much currency as it wants?
Taxes are a tool that help regulate inflation and reallocate financial capital. Hypothetically, yes the government could simply print more money to fund public services, but the amount of money needed would probably cause some sort of dangerous inflation.
Given that States with a sovereign currency don't actually need to tax to fund themselves, then taxation performs some 'other' purpose. Taxation is a much more effective method of handling inflation, than interest rates, because taxes can be tailored to target the inflation causing areas of the economy, this is currently impossible with interest rates. Also since America, and most of the world is experiencing economic difficulties, taxation combined with spending, can reallocate money that is not being spent to areas of the economy that will cause spending. That is, taxing people with large sums of money, and giving it to people who will spend. For each financial exchange between people there is a corresponding 'real' exchange between people, and this exchange is the source of economic growth.
Government spending would be 100% inflationary, but taxes are a way of destroying money, which sterilizes a portion of the spending. I won't comment on the notion of stealing from the rich and giving to the powerful in the name of the weak beyond saying "ick".