We already (mostly) solved that problem in the US with the Fairness Doctrine. Then we apparently decided because the problem was solved, we didn't need the regulation anymore. That ended exactly as you would expect, and exactly as it has every other time a regulation that's working is removed because it's "not necessary anymore".
I wonder what would happen if we tried applying that today. For example, would climate change qualify? Scientists are pretty one sided on it, but politicians and the general public are not. So does it have to be controversial for the experts, or for the general population? I can also think of issues where scientists aren't in agreement but the population mostly is. What about if there are numerous different sides to an issue? Imagine giving fairness to some religious matter, given how many different religions there are.
Overall, I just have a hard time imagining the details of how it would apply in today's world.
https://en.wikipedia.org/wiki/FCC_fairness_doctrine