Why is Roundup still being sold at Homedepot and Lowes?

The case against Roundup is real but not airtight. Even in a worse-case scenario it is less toxic than many other herbicides. Occasional exposure to it is less risky than occupational exposure.

My take.

I prefer mechanical destruction of weeds, mulching, etc. to the use of herbicides.

We have a bottle of Roundup around to use on poison ivy; not only do you not want to touch poison ivy, but we have very little of it on our property and we think we can eradicate it.

Other than that we don't use herbicides. If we grew corn and were serious about it we might use 2,4-D.

I don't recommend herbicides at all for lawn and garden use. Chemlawn goes and sprays a mixture of chemicals indiscriminately and it doesn't make a lot of sense. Suburbanites think they have to do it because frequently the topsoil was scraped away when their subdivision was built and their lawns and not well established. A well-established lawn is the toughest enemy weeds can have, but it is sad to see what happens if you try to grow a lawn without topsoil.

Because most people don't know or don't care. People buy stuff all the time that's bad for them and bad for the planet.

Why do people still buy & smoke cigarettes?

It's profitable.