Sweeties, Pies and Ginger

You know the advert, washing machine repairman inside a launderette when in walks a very flustered woman with all her washing. Repairman eulogises about the fact she should have used Calgon with every wash to prevent her machine breaking down, while showing us a furred up heating element. Shouldn't he be telling the launderette owner to use Calgon...? After all, he's just removed said furred up heating element from one of the machines at the launderette. If Calgon made that much of a difference, don't you think all the detergent manufacturers would put in their products...?