> If politicians get to call the shots in any way, it's going to run way over budget. Pretty much every single time.

This is nonsense. It's just that infrastructure projects that get delivered on schedule and on budget (or somewhat close to that) don't make for equally pretty HN headlines.

There's a lot of public infrastructure around. The vast majority of it was commissioned by politicians. The vast majority of it is just there, mentioned a few times in the local rag before commission and upon opening and that's it.

Sure, I wouldn't be surprised if public spending is more often out of budget or behind schedule than private spending like you suggest. But even then, Berlin Brandenburg is an exceptional case and suggesting that excesses like it are inevitable when politicians were involved is just nuts. There's plenty of competent politicians.