"...and if you don't allow me to use your employee toilet and direct me to the public toilet next to the store I'll flip my shit and start kicking the door."
Hot take: businesses should have to pay much higher taxes if they don't have public (including the homeless) restrooms. The default is being allowed to go wherever we want, and now they just expect you to go "somewhere else".
I don't own a business, and assume you understood what I actually wrote.
But let's say I did own a business. In that case, you're right to point out that providing a restroom unilaterally would make each business owner worse off. That's why it would require a tax incentive, not just asking nicely.
The homeless are going to poop somewhere. They don't have money for pay toilets. Wherever they go will require cleanup, and it's better for everyone if that's a restroom than if it's the sidewalk.
The people doing the abusing here are not the homeless.