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And there are hundreds of thousands of un(der)employed decaying middle class men.

Who used to fix sidewalks among other things.

"You just need a ton of money to keep sidewalks in good order. "

No, you don't. You just need to make them properly the first time and keep people from planting trees where they don't belong.

In my parents house in Canuckistan, I've never seen them fix the side-walks in 20 years and they're mostly fine.

I read your comment to see why you were down voted. The first paragraph is fine. Although, as an Italian, I beg to differ. The Romans were quite capable of building roads that are walkable 2000 years later. Not all. But it is 2000 years.

Then I read the second one. Wow. You've internalized the "have bad infrastructure and get an SUV" mentality. We're not paving the world. We're paving a small part of our environment where people live. Yes strollers have stupid wheels. But having good infrastructure in a small area means I don't need a techno-distopian robot walking me everywhere.

1) "the whole point of DU is that it's significantly less radioactive than naturally occurring Uranium"

The D in Depleted (U-238) has nothing to do with it's radioactivity but that it's not fissile. Fissile U-235 is not too badly radioactive either (4 billion vs. 0.7 million year half life i.e. 77% more radioactive 0.5^(0.7/4) / 0.5).

We don't make depleted uranium to have less radioactive uranium (naturally occurring uranium is < 1% U-235). We have DU because we made nuclear bombs.

Interestingly the Ruskies have made DU arms far more expensive now with their breeder reactor (U-238 is fertile).

2) DU is an alpha emitter. I would bath in a bathtub made of alpha-emitters and sleep in a bed of alpha-emitters.

However, Uranium shatters making dust. I would not want to breath, eat, drink an alpha-emitter. It's a heavy hitting He ion that will knock the socks off anything in it's short path.

Not to mention U-238 becomes Th-234 with a half life of 24 days (very radioactive) with beta emission (ouchy!). There'll never be a lot of Th-234 (U-238's low radioactivity) but it'll all decay into you (Th-234 small nuclear half-life and large biological one).

So U-238 effectively decays in your body as a an alpha and beta!

What happens when you blow up DU? Gets scattered throughout the local environment.

3) ...Low biological half life

That's only relevant for disaster tourists. For people whose environment has been seeded with the stuff, the biological half life is completely irrelevant as it is replenished as you eat, breath and drink. An equilibrium concentration is therefore established.

Therefore, environmental half-life is far more important than a biological one.