how do they decide where to put bus stops?

If I had to guess, there are likely traffic studies done before the business get created to find most popular routes.

For existing routes, I was able to get one that was in front of my house removed because there was another one 60 feet away and not in front of a residence. I'm guessing getting one added might be a similar request.

If you need one, reach out to your local transit and ask them. Doesn't hurt to ask!