One reason that military spending is very high and it is hard to redirect underperforming military procurements is that military spending is deeply enmeshed with political considerations. These include job creation and maintaining sovereign capability in key industries. Those can be legitimate, but our political system can end up unproductively conflating the separate goals: you might spend more than you would have on a simpler jobs program, while simultaneously getting a worse military outcome, by trying to achieve both goals with a single huge program.
Even if you start with the presumption that government should invest a huge amount in domestic job creation, tied to strategically valuable sectors, this does not make military investment the only option. It's interesting to consider what a broader 'resilience-industrial complex', replacing today's narrower 'military-industrial complex', might look like.
Some aspects might include:
Funding industrial investment and jobs in a broader class of resilience-related goods, spanning healthcare, disaster relief, and infrastructure. If you need to create jobs in aviation, bombers are not the only option: why not build more air-tankers for fighting wildfires? If you need to create jobs in manufacturing, why not explicitly focus on developing domestic supply chains for critical healthcare goods so that they're not so scarce in times of crisis like we've witnessed?
Industrial Security Policy: New Missions for DoD, SBA and CFIUS
Some companies are making this flag-waving pitch already:
Funding sovereign manufacturing capacity in a way that encourages general upskilling and maintenance of the industrial base to promote dual-use capability that can be tapped for security later. By this I mean: don't necessarily keep building tanks that are only useful in wartime, instead build a lot of trains that are useful in peacetime and also ensure that you have factories and skilled workers that can be quickly converted to building tanks when needed. Meanwhile, if you aren't at war, you're still getting use out of (or profitably selling) the trains.
The book Freedom's Forge is a great discussion of American manufacturing as the 'arsenal of democracy' in WWII, and one thing that's obvious is that their success was not driven by having a huge armaments industry before the war. In fact, it was quite anemic after years of post-WWI neglect. But a strong general manufacturing industry, including companies with expertise in mass production, machine tool manufacture, and managing complex subcontracting supply chains, was able to be redirected to armaments with great effect.
All in all, the Ford Motor Company would produce more war materiel than the entire economy of Mussolini’s Italy.
In the end, American automakers would produce 50 percent of all aircraft engines, 35 percent of aircraft propellers, 47 percent of all machine guns, 87 percent of all aerial bombs, 80 percent of tanks and tank parts, one-half the diesel engines for ships, submarines, and other naval craft; not to mention 100 percent of U.S. Army trucks, half-tracks, and other vehicles.
Freedom's Forge: How American Business Produced Victory in World War II
In the modern day, we might look at industries like electronics, energy (photovoltaics and batteries), UAVs, and so on as areas where we can encourage a strong civilian industry without only investing in armaments, but which strengthens our security-relevant industrial base for use when needed. One example is the fact that the US apparently has limited ability to make the most advanced types of semiconductors - Intel makes some, but most are made in Korea by Samsung and Taiwan by TSMC. (Australia has none of this at all.) This lack of manufacturing capacity becomes a military risk given the proximity of that supply chain to China. Funding advanced semiconductor manufacturing in the US thus increases resilience and is security-relevant, but has the added benefit of being useful even if the US is not at war, because advanced semiconductors can be used in civilian applications too.
Chips and Geopolitics – Stratechery - Taiwan semiconductor manufacturing in US
Argument for investment in civilian shipbuilding
Don’t Buy Warships (Yet) | Proceedings - June 2022 Vol. 148/6/1,432