Apple and Google have published a protocol for privacy-presercing contact tracing - https://www.apple.com/covid19/contacttracing/
They use a decentralised approach where the 'matching' process take place on the users handset.
However, the UK and France have said they will instead use a centralised approach - https://www.bbc.co.uk/news/technology-52441428
Where the matching occurs on a centralised server.
There is a claim that this allows 'better auditing', but I don't know what that means.
My question is what is the advantage of the centralised approach?