Perhaps they didn't know about the checkbox and thought they had to write a custom solution. It could also be that they knew about that really subtle bug that i

Perhaps they didn't know about the checkbox and thought they had to write a custom solution. It could also be that they knew about that really subtle bug that is caused by un-checking that checkbox and thus understood why that didn't actually solve the problem long term if though it looked like a good solution at the time. Or perhaps they're so used to getting away with quoting 6 month for a 6 hour job, it never crossed their mind not to.