Pesticides, which in includes herbicides and “weed killer” are poisons. They are harmful to human health.
Think about it. If you have dandelion in your yard and you jump up and down on it, and pull its head off… it survives. A human being would not. It takes a lot of strong poison to kill a dandelion. And the poison doesn’t magically disappear in a few days, or after it rains. Most of the weed killers sold to homeowners in the USA are illegal in Ontario Canada, because they are harmful to human health.
People have been brainwashed into thinking that we must have lawns, and that they must contain only grass. I disagree. If I see a lawn with dandelions, I believe the homeowner cares more about the health of his or her family, than about having a weed free lawn.