I agree that people should be angry: the UK's excess deaths per million exceed those of comparable countries and the government has not done enough to protect workers. But as recent history teaches us, the fact that something should happen doesn't mean it will. There are reasons for the lack of anger.
One, I suspect, is that in crises people tend to want to pull together and not to rock the boat.
There are two other things that come from my day job that might be relevant here, however.
The first is suggested by research by Christoph Merkle. He found that UK shareholders just after the 2008 financial crisis were much less upset by their losses than they expected to be. One reason for this was that they realized they were all in the same boat – and a troubled shared is a trouble halved. Another, though, is that we quickly become accustomed to bad times. We adapt. That lessens anger.
Secondly, a common failing of retail investors is to hold onto losing stocks too long in the hope they'll come good: this is called the disposition effect.This is part of a wider habit, known as choice-supportive bias or post-purchase rationalization. We hate admitting that we were wrong. To avoid this, we invent reasons why the dud stock we bought will come good, or why the car we bought is in fact a great one.
Likewise, voters don't like admitting, even to themselves that they were wrong. And if we don't want to believe something, we easily find reasons not to. As Leon Festinger showed, people can stick to their beliefs even after they have been falsified.
In a sense, though, Tory voters have not been proved wrong. Nobody ever seriously pretended Johnson was competent or diligent. Voters didn't want a technocrat, and they haven't got one. People voted for him merely because he'd Get Brexit Done and was not an anti-semite. And he's fulfilled expectations. He's the Ronseal Prime Minister, doing exactly what it said on the tin.
We typically feel anger not so much as mere incompetence but at injustice or treachery: there's a reason why the hatemonger Farage wants to depict any slight concession to reality as "betrayal". From the point of view of his supporters, however, Johnson has not betrayed anyone. So there's less reason for anger.
And then there's simple tribalism. I might moan endlessly about the Arsenal. But when confronted with a Sp*d abusing them, I leap to their defence. Similarly, Tories faced with "woke" lefties attacking Johnson will support him. In this context, Starmer might well be wise to soft-pedal his criticisms of Johnson. Doing so provides space for the Tories and media to peel off from him. It deters them from circling the wagons.
There are, then, good reasons why much of the public has been passive in the face of the government's incompetence.
Whether this will continue, however, is impossible to say. The recent surge in protests by the Black Lives Matter movement shows us that anger can simmer beneath the surface largely unnoticed by the media and politicians until a trigger causes it to explode. Threshold models of the sort described (pdf) by Mark Granovetter might be relevant here. Some things can be explained but not predicted.
How the world really is, and how we react to it, are two very different matters.