Everything you say is just opinion unless you post links to show the scientific studies you claim.
You say human parasite tests are flawed, but vet parasite tests are accurate because they "test and examine on the spot". If people here think they have parasites, then I guess they should go to a vet for confirmation.
A lot of you make the argument that parasite lab test for humans are flawed because you theorize that they are low-paid workers and argue who wants to dig around poop samples to try to find microscopic evidence of parasites, but the majority of people here who think they have parasites believe they do because they swear they saw worms, flukes, or whatever in the toilet with their own eyes. If those objects are parasites and are so big that even sick and desperate people can see with their own eyes, then there's no logical argument why doctors or lab techs couldn't confirm it if those people brought those samples from the toilet to them other than those objects weren't really parasites.