That no longer works when the adversary has any sort of credible air defense. Can't risk manned aircraft at low altitude any more.

Pretty much all ground attack aircraft that aren't just multi-role fighters with precision munitions hanging off of them are crap if you don't have air superiority.

OTOH, an plane with a very precised gun may "win" an encounter by circling above a well-defended area, having SAMs shot at it, shooting down the SAMs as they approach, while being cheaper to operate (and replace when it eventually does get hit) than the missiles shot at it.

While at the same time occasionally dropping bombs at targets to make ignoring it not an option.

The defender in this scenario has a seriously disadvantage, in that the local SAM sites can send many missiles at the same time, and the anti-missile suite of the plane has to defeat every single one. A gun that would succeed in this scenario would be a massive technological leap. The US Navy uses gun-based anti-missile setups, but they are more of a last ditch sort of defense that can defeat a small number of incoming missiles by putting an absurd amount of bullets in their way.

> can send many missiles at the same time, and the anti-missile suite of the plane has to defeat every single one.

That's what makes unmanned planes special: It doesn't. It just has to force enough missiles to be fired that the missiles are more expensive/valuable than the plane when it ultimately gets shot down.

(Value can be different from financial cost, depending on e.g. supply shortages, influence on the rest of the war, etc.)

The plane is the attacker, unless someone invaded their home and put SAM sites everywhere while they were out.

You can bet we will be risking manned aircraft and low altitude for a very long time to come. I don't think you understand military priorities in times of war.

Sure they will take the risk at low altitude when there's no other option. But the preferred technique now is to orbit at medium altitude and dispense precision munitions. Why expose the aircraft to ground fire when it's not necessary?

We can and we will risk manned aircraft at low altitude against a credible air defense. The war just has to be meaningful enough.

Nazi Germany had a credible air defense. We sent bombers anyway. At one point, the expected lifetime (survival) of a bomber crew was a month.

It has been some time since we fought a war that was worth that risk.

There is an interesting angle on modern great power conflict. Even in a non-nuclear war, all modern combat systems, munitions, and manufacturing bases, would be destroyed or expended within the first weeks by precision munitions. Pro-longed non-nuclear conflict would likely require tradeoffs towards lower-tech components that could be manufactured in more locations at lower risk of bombardment.

They're ultimately just aren't that many aircraft or cruise missiles in modern militaries relative to WW2, and they each cost 2-3 orders of magnitude more than their WW2 counterparts (although the cost increase matches the capability increase).