It might not sound like much, but the French people who committed the prison concrete sabotage weren’t ordinary people who showed up with sugar in their pockets, they were a well organized group that had also broken into offices to steal construction plans. One of their documents describes sabotaging the concrete as “a simple matter” of adding sugar, but that’s all - it doesn’t say whether they added it to a running truck (which would be quite a trick because everybody on a truck crew knows who’s in the crew) or mixed it dry with sacks of concrete in a storeroom, or what. It also doesn’t mention observing any actual results. People’s vision of how this would work is way too simple - “Just toss a 50-lb bag of something into a truck!”