Comment 8 for bug 988870

You are right, these buildings (mines and carrier animal farms) have conditions like: "return=skipped when economy needs <input> and not economy needs <output>". I guess this is when the input is infinite so that the player never should lack of it. But this way leads to the described behaviors:
- Too few thatch reed if the target quantity is too low
- Other mines do not get enough food if the player has many coal mines (e.g.) and too few taverns (or whatsoever)
- No water and wheat are stored, but useless carriers are created

Other buildings, where the input resource is limited (e.g. all smithies) have a condition like: "return=skipped unless economy needs <output>". With this condition, a ware is only created if it is needed to fulfill the economy request, but then in every case. This might lead to problems that cloth is produced (and therefor thatch reed is consumed) although the thatch reed would be needed for buildings. But I do no think that this is as critical as the other option because as soon as one has enough cloth, the thatch reed will be available for other projects.