Today at work I got to sweep the entire parking lot (this is a 24-pump gas station at an intersection of I-20) and I had the idle thought that perhaps the removal of ashtrays from cars, more than anything, just helped make cigarette butts one of the absolute staples of roadside pollution.
I mean it's not an excuse for the people doing the littering because if you want you can get a bucket ashtray that fits in one of your cupholders for like $5 at any smoke shop but I'm sure it didn't help.
and it's not like they're a useless waste if you don't smoke. They're also good as a small trashcan for stuff like wrappers and napkins - items which also comprise a lot of roadway trash.
Really though you should just be charged $50 every time you throw trash out your car window. I think your car should snitch on you about this, I think traffic cameras and toll cameras should snitch on you about this, even the pigs should be in some way incentivized to enforce this stronger.