The Fed can do this at all right now because we created a body of subject-matter experts and deputized them to pull the trigger without having to check with anyone. This is a rare thing in a democratic government, and is possible mostly because we have given them boring powers that only wonky people bother to even read what they are. Even then, a few people read what they are and complain about them, so even that is a bit perilous.

If you wanted the Fed or a Fed-like mobilization for the helicopter money you first need to make the process of getting $1000 boring, or wonky, or at least politically uncontroversial so that people accept an unelected body of bureaucrats outside the government process doing it unilaterally in the middle of the night without telling the rest of the government. I would not rule out those conditions being the case at the end of this crisis, but they aren't the case at the beginning.

But the way we solve political problems (or, more recently, the way we don't solve them) is through Congress, which is an inherently slower approach.

One, it is not targeted. The Fed can pump vast quantities of liquidity into the heart of the credit markets in a way private actors aren't set up to.

Two, it is not fast enough. Companies will go bust while waiting for politicians to authorize a cheque, the Treasury to cut it, investors to cash it and then to identify and decide upon an investment.

Three, it isn't reliable. Investors trust the Fed's discount window will be open in a crisis. That knowledge, itself, stops many runs before they start.

Four, it's riskier. Helicopter money cuts cheques. Once it's done, the money is out the door. The government is never getting it back. If they sent out too much, we'll have inflation. Monetary policy involves collateralized loans. The collateral limits downside. And unwinding a loan is easier than raising taxes to drag surplus cash out of the economy.