I live in SF, and I am not homeless but still struggle to find somewhere to use the restroom without buying something I don't really want or need in a restauran

I live in SF, and I am not homeless but still struggle to find somewhere to use the restroom without buying something I don't really want or need in a restaurant/bar/whatever. More than once, I have purchased something or just tipped someone merely because I needed to use the restroom. I frequently struggle to find somewhere to throw things away. I have walked several blocks (probably close to half a mile) carrying my dogs poop simply because there is nowhere to discard it. I am not surprised that the streets are full of trash and human excrement. I have a place to go home to, and frequently hold it until I get there. I have a lot of empathy for those who live on the streets; I don't think anyone really wants to shit where they live, it's a matter of necessity. Where would you relieve yourself in SF if you didn't have a home or money to needlessly pay someone to use their restrooms?