By “parasites” I think you mean our fellow human beings, but there are some better arguments than that. One is delaying preventive care can lead to more serious (and expensive) health crises later. Another is that able bodied people younger than 65 don’t use that much health care in the first place, so trying to create a compliance system might cost more than the savings.
Another is that jobs meeting the hourly requirements may not exist–especially in rural and economically disadvantaged areas. Which by the way is where many of the able-bodies recipients are coming from.