I'm afraid the US government and AAPL are very different things.
Apple does not have its own currency, nor powers to raise taxes, so its capacity to effect change on its environment is largely determined by its cash pile. It is now, like Porsche, essentially a hedge fund with a retail arm (Braeburn Capital, AAPL's fund, for the story read this article on zerohedge. Also the story of Porsche's billions on BBC News)
The US government, by contrast, has rather more resources at its disposal. The balance is negative (as with probably every country) in that it has $10tn debt and $3tn reserves. But that doesn't entirely matter; the markets will continue to buy Treasury bonds by choice, and if they stopped the government could start forcing them to hold bonds. The US government has other resources; the US economy and the taxes it can raise, military resource, positive international relations, and importantly its strong history of not defaulting on debts.
Unlike a retail company, a government would be chastised for running a positive balance; why are you taxing everyone so much if you don't need the money? Only absolute monarchies and dictatorships extract more money from the populous than they need. The caveat here is that recently AAPL did return some of its cash pile, at the prompting of some of its investors.
Comparing the cash reserves is also fallacious in that the US government (by which I include Congress) can print more money if it needs it, as long as the effect isn't strongly inflationary, whereas AAPL cannot.
Really the US government is more like the property management company of a rich gated community. It doesn't matter that the property management company has a relatively small reserve; if resource were needed for security or maintenance, the community would come up with it. The US apparently has a net worth of about $123tn, whereas Apple has total equity of $123bn, so 1/1000th of the value.