Such rules don't work. The UK does have such rules still written into law and the BBC's charter but they are simply ignored. The regulators are fully captured and act as enforcers of the chosen agenda, e.g. at the start of lockdowns Ofcom created a new rule that broadcasters weren't allowed to question government health advice!
Fox is not the problem the USA has. Fox is the solution. Would all the people who think news media is untrustworthy be lapping up CNN if Fox didn't exist? Again, other countries provide the answer - no, they wouldn't. They would just assert that all TV news is biased and refuse to watch any at all, whilst simmering in anger at the system that tries to eliminate them from public life.
All American broadcast media would be illegal under an actually strict interpretation of such a doctrine, which is why such doctrines are never actually enforced as written. The fairness doctrine would not make US media "fair". It would be exactly what it is everywhere else that tried this - state censorship of viewpoints that upset the establishment. I understand that fact very well indeed, given that I can and do directly compare media between a place that has such a rule and places that don't. Congress was correct to abolish it. The UK should do the same thing.
Fox is not the problem the USA has. Fox is the solution. Would all the people who think news media is untrustworthy be lapping up CNN if Fox didn't exist? Again, other countries provide the answer - no, they wouldn't. They would just assert that all TV news is biased and refuse to watch any at all, whilst simmering in anger at the system that tries to eliminate them from public life.