It's not about accuracy, weather data us provided by the government in most countries, the third parties are using the same data. You could make a case for better UI or UX but not really data...
Every government has to have e weather service since it's vital to agro, fishing, daily life etc. But they can release the API or whatever that doesn't drive out of business other weather companies.
They are trade rules: for example, if USA subsidizes Boeing they can be sued and fined in international trade courts, since it hurts, say German companies. (Chinese companies, Airbus etc are routinely accused of having an unfair advantage, due to government subsidies.)
But the cases you mention are about the Government helping a private entity make a profit. In the weather app's case it's the Government (broadly speaking) giving tax payers something "for free". This last case is far more nuanced than your comparison makes it out to be.
And I'm pretty sure most tax payers will pretty much always choose a free app that gives them basic weather data a few days in advance than a paid app that gives them bells and whistles. So the Government is catering for the vast majority in this case.
