> I've never seen a smoker throw their butts anywhere but the ground.
This is one of those areas where you get much better (far from perfect but better) results if you make the right thing to do the easy thing to do. It doesn't take much to make smokers happy, a large enough area for them, some cover and some ashtrays, do this and people will generally use ashtrays. These days so many places are rushing to vilify smokers and push them out on the street, when you're out in a side street getting your fix, maybe getting rained on or baking in the sun and don't have an ashtray or bin in sight then the ciggie butt is going on the ground.
It's like complaining about litter but not providing bins.
Of course you can solve it with incentives, but you place the burden on restaurant owners and cities to place bins everywhere. Note these are different from regular bins too. And even then you will still get people that fail to use them.
Imo, the effort, or financial cost should be with the manufacturers as OP suggested to modify their product.
This is one of those areas where you get much better (far from perfect but better) results if you make the right thing to do the easy thing to do. It doesn't take much to make smokers happy, a large enough area for them, some cover and some ashtrays, do this and people will generally use ashtrays. These days so many places are rushing to vilify smokers and push them out on the street, when you're out in a side street getting your fix, maybe getting rained on or baking in the sun and don't have an ashtray or bin in sight then the ciggie butt is going on the ground.
It's like complaining about litter but not providing bins.