This is exactly the topic of my PhD on corruption in government procurement processes (a pandemic endeavour). My research shows that corruption (which includes conflict of interests such as the PwC example) are not only about bad apples (individuals to blame) but also bad barrels (organisations to blame) and bad orchards (institutions or whole sectors such as the consultancy sector to blame). It's so frustrating to see organisations lay all the blame on individuals when they (the organisations) have set a corporate culture that tolerates, ignores or even encourages that corrupt behaviour, and when a whole institution (eg the military, the police, the public sector) also tries to duck out of its responsibilities for controlling and directing the integrity of its members, both individual and and organisational.
Edited to add: This really cheeses me off. Just to keep it on topic