As every ballot station count only his ballots, it's quick.
For a presidential election, maybe 30 minutes.
The counting is done by the citizens, so no (easy) frauds are possible.
All ballots are visible, the process is transparent, no suspicion.
I personally think that a 30min delay to get the election results is worth the wait.
The recent change has to do with how the votes were tallied. Basically the way they were transmitted wasn't really tamper-proof, and there wasn't a system in place to determine the difference between the result of the ballot station and the publicly announced result.
Of course they've 'solved' this by replacing the electronic tallying system. Which I can't help but feel is a very misguided way of fixing those problems.
It is about what happens after that. The electronic steps after that are deemed not secure enough.
Raw numbers of each station are available publicly. The people who did the counting can check if their numbers were transmitted correctly. Parties usually have preliminary results from their people at stations way before the centralised system processes & publicises them. They'd easily spot any issues. Paper ballots are stored in secured bags and can be recounted if there is a need.