That's actually not what "50% chance of rain" means.

Here's a pretty good explanation:

https://www.wsfa.com/2019/08/23/what-does-chance-rain-really...

And many more:

https://www.google.com/search?q=50%25+chance+of+rain

That is absolutely not "we have no idea". It's a very precise prediction, not like a [10%-90%] range. If you look at all their 50% prediction, the half of it should be rain and half should be no rain. This is what this number tells you.

Predicting 50% can be validated: if I say a coin will be heads 50% of the time, I know more than nothing: I know more than someone who incorrectly claims it will be heads 75% of the time.

And we can quantify in various ways how much better the 50% prediction is than the 75% prediction.