The bankers' union, sorry the Australian Banking Association, went into full swing. "We haven't even been consulted!" they cried. The nerve of the government, enacting policy without even asking permission ??? They weren't alone, though. Some of the big business lobby groups also leapt to the banks' defence.

Though why, and under what circumstances the tax was unfair or inappropriate wasn't exactly clear. It didn't stop the hand-wringing and fear-mongering, of course. To be fair, if you're a lobby group, that's what you're supposed to do. But it seems - thus far at least - that most Australians and our politicians are treating it accordingly.

These are the banks, for the record, that have some of the strongest operating metrics - and government protections - in the world. It's hard to make a decent argument that they shouldn't pay some of that largesse in tax - other than an argument of naked self-interest, of course.

No, the world isn't going to end. No, the rest of the planet's business community doesn't suddenly think Australia's government presents some sort of existential risk.

For the record, there's also no clear and present need for the tax, either. Or, at least not that specific one. The banks didn't deserve to be punished (at least, not just for being profitable), and the money raised is going straight into consolidated revenue, not put aside for some sort of bank collapse fund.

But, on balance (if you'll excuse the fiscal pun), the government had a budget that was spending-heavy and revenue-light. It needed to find a way to raise funds, and the combination of policy and politics meant the nation's largest banks were in the firing line.

But back to the warning (or lack thereof). Frankly, any industry that thinks it has a right to be consulted before governments enact policy has been eating at the big table for too long. What the bankers really mean is 'We didn't have a chance to talk you out of it'. And nor should they have.

Business the world over seems to have developed an entitlement mentality that it decries from others - somehow it deserves to be consulted on policy and to receive warnings from central banks months ahead of policy action. It's no bad thing that the government has reminded them that it runs the show.

And, for the record, that's coming from an unashamed fan of democratic capitalism.

It's a strong and unvarnished reminder, too, for individual investors, that the unexpected can happen. And will happen. Without warning.

We've seen its ilk before, too. Remember Kevin Rudd's planned crackdown on salary packaging? That hit McMillan Shakespeare's shares for six. The government crackdown on for-profit education providers? What about the removal of Medicare bulk billing incentives for medical testing companies (which was - as unexpectedly -- reversed in this budget? And it's not just government decisions, either. The global financial crisis came from (relatively) nowhere.

Foolish takeaway

What's the solution? It's certainly not giving the investing game away because of the uncertainty. That would be to dispose of the infant with the bathing solution. The answer, instead is two-fold. First, understand that these things happen, but that trying to predict them is silly. Then, armed with the "known unknowns" as Donald Rumsfeld would call them, invest anyway, but thoughtfully.

Plan. Prepare. Diversify. Take a long view. Invest as if there will be shocks, knowing that, on the other side, will be success for the patient, thoughtful investor.

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Scott Phillips is the Motley Fool's director of research. You can follow Scott on Twitter @TMFScottP. His email address is ScottTheFool@gmail.com. The Motley Fool's purpose is to educate, amuse and enrich investors.