I have a Naive question, "why aren't the discussions related to public matters be telecasted live like a football match to the whole world? why isn't the public privy to the discussions about its own future?"
It gives the parties more room to manoeuvre with regards to the give and take that is often/usually necessary when it comes to negotiating. If you demand X at one point, but revert so you can get Y, then the absolutists will be outraged (either actually or performatively) that you are being "soft" and "weak", etc.
There are a lot of people who think in zero-sum, winner-take-all ways, which is generally not how the world of foreign relations works. And modern-day outrage machine will create more difficult situations if you give here and take there (ignoring the fact that the other side gives there and takes here in return) even though it may be necessary to get a result (even it it's not perfect).
A party can always disclose what's going on in negotiations.
This is generally not done as it is often is a violation of trust, but if there's no good faith there in the first place it's hardly a loss. Negotiations can always be broken off with the reason being "the other side is not negotiating in good faith" without particular negotiated-to-day conditions being released.