"Grab 80 million people and claim they have some psyche in common, people love reading this stuff"
I find the issue with candour is mostly with casual conversation or casual issues. The 'big lies' I think happen just the same.
Corruption in UK is about the same as Germany.
UK is super deferential and not candid, i.e. 'it's not polite to point out ugly things', but this might be perceived as duplicitous in 'candid' countries.
An English person might say 'that's interesting' instead of saying 'it's shit', to be polite.
But in terms of how it breaks into level of civility, it's just the same really. 'Transparency International' ranks them the same in terms of corruption.
So I think it's more a matter of immediate, interpersonal communication than anything.