While the example given is adding complexity to the data and trying to model that using the type system I think the point holds in may other cases. Take betti

While the example given is adding complexity to the data and trying to model that using the type system I think the point holds in may other cases. Take betting as an example I work on. The basic idea is that if a bet wins you get paid your stake multiplied by the odds of the bet. If I open the codebase it should be trivial to find where that multiplication happens right? It's such a fundamental part of the code. But actually the edge cases (starting price bets, each-way betting, handicap betting with split line handicaps, multiple bets, dividend bets) mean it's very difficult to point to exactly where that happens. If I had to guess 90% of the code isn't needed at all in the majority of bets which are singles or straight accumulators.