German here. Big infra projects here rarely fail due to corruption. The way, way bigger issue is that in the last 30 years public service funding was drastically cut which meant that the oversight competence over projects was no longer in house. Overworked officials rubber-stamp utter bullshit because they have neither the knowledge nor the time to properly audit plans. Not just architectural or technical (hello BER fire suction system), but especially financial.

The mandate from the EU is that all kinds of stuff must be offered via tender europe-wide which is for many things a colossal waste of money and enviromental resources (e.g. a Polish company wins a tender for a construction project in Spain and now has to move all the machinery and staff through Europe and back, that's NOT sustainable!), and while government entities are allowed to judge bids by sustainability or profitability (i.e. purposefully offering an unprofitable bid in the hopes of making the profit with exploiting "change requests"), they rarely have the knowledge to do so.