But, we’re still in a world where 100% of the population are toons, when there aren’t out-of towners visiting. If the toons are anything like us humans, they presumably watch both watch films with all cartoon casts. I think the screen as a teleportational device makes sense to me and I would think (similar to real world Chinatowns) that there are multiple Toontowns spread all across the globe in the Roger Rabbit universe (I know the original book is different, but I believe that’s alluded to there).
Just as a transporter would be insanely useful to people (as long as you keep the flies out), I imagine traveling by screen would be insanely useful (plus I feel like it makes sense considering the fourth wall breaking nature that many cartoon characters are known for)