The cost of fecals is so nominal it is not a money making racket for any vet - in fact, selling you on unneccessary de-worming would be much more lucrative for them. The point to using fecal guided treatment is to try to avoid the very issue that exists today with the ever increasing issue of resistance in the parasites due to the overuse/misuse of deworming medications.Of course they do, because they get to charge you money for fecals. There are cases where a fecal is needed for a difficult diagnosis, but that's not the norm. However, if you have extra money to spend on several fecals per year, it doesn't hurt.