In a perfect world, that would be enough. But lead paint workers, like all workers, can get careless from time to time. If a worker comes out of containment covered in dust, takes off the coveralls in the cleanup area, but then doesn't wash his face and hands before going to lunch, he's going to ingest lead from his cheeseburger. Smoking a cigarette with lead dust on it is particularly dangerous. Particular care must be given to leaving the clothes, gloves, etc., at the worksite.
Children are extremely sensitive to lead dust, because their nervous systems are still developing.
There are other difficulties with hygiene, such as with using compressed air to blow dust off workers, or with using HEPA vacuums on clothing, that are too complex to discuss in this space. But they're there, to be sure. And this is not to say that tiny amounts of lead dust will make you keel over. Lead will affect different people in different ways. Yet basically, a worker still has to treat lead dust like it's radioactive.