The elections being discussed are performed over the internet, on the voters own computer. Where would the paper audit log be created, and how would you ensure it accurately reflects what the voter chose on his (possibly compromised) PC?
Edit: See the answer by user relix in this thread. This system does not solve the two issues I raised. As with all of these systems, they have to choose between "secure (verifiable) ballot" and "secret ballot". Estonia has clearly chosen the former.
The problem with that is that now people can be pressured to vote in certain ways, as they can prove after the fact how they voted. This has not been a big problem in first world countries for a long time - but I don't think that's because people have fundamentally changed, but rather that nobody tries it because the paper ballot system effectively stops such voter intimidation/manipulation.