> The thing is, fundamentally there is very little difference between a truck, a bus and a tank.
I can see your point, but I'm not buying this argument for multiple reasons.
First, if you do blanket-protectionism like this, the actual strategic gain per "wasted" tax-dollar is abysmal. You could have just bought those singaporean busses, and spent the money on skunkworks and lithium mine subsidies instead if you actually needed that resilience and military capability.
But secondly, I would argue that you really don't. What kind of war are you even anticipating where you would need massively scaled up tank production of all things? The US, currently, could fight an offensive land war against the whole continent pretty much (regardless of foreign support), and for anything else tank production capabilities are more than sufficient.
Being independent sounds really good on paper (and looks appealing when glancing e.g. at the European gas situation), but isolating your nation economically has a really shitty track record, historically, especially when you are not sitting on top of a global empire to circumvent some of the drawbacks.
> we need to make sure that our populations actually get some more of the wealth and income that is being generated every year so they can afford it, like in the past!
100% agree with that, but I think this is a (tax) policy failure most of all: my take is that in a capitalist society capital inevitably accumulates at the top, and regulatory backpressure (progressive taxation and antitrust law) is needed to keep the wealth/income distribution somewhat stable; the US has been shitting the bed in that regard for more than half a century now with predictable outcomes for wealth/income distribution (similar for other industrialized nations). Redistribution/balancing dynamics ("poor people getting paid for labor") are also getting weaker because unskilled labor lost lots of relative value.