Problematic Counting in Colombia?

An economist and a physicist ask about the quality of the counting of the ballots in Colombia given how close the election was. Based on research about vote counting, they catalog the ways in which human error could have happened, especially as the counting was occurring quite quickly.

In total, therefore, the result presents as many as 400,000 opportunities for classification mistakes. That’s before counting any systematic human behaviours not listed above. This represents a numerical uncertainty that swamps the victory margin of 53,894.

Hmm. This raises the question of whether recounts are possible. That does seem to be the case, as votes in a senate race were recounted in 2014. The next question, then, is why have the "yes" supporters not mentioned this as a possibility? I have heard nothing.