Buffs are in the jungle therefore distribution is judged by jungler
Same goes for all camps really. You may think "it's just one camp," but if all 3 lanes say that, then I only get one, and I don't have a lane full of minions to go far. If you're 50 gold off last whisper and they have a ton of armor and all lanes are pushed, fine, just ask, don't simply take like it belongs to you.
Now the real point of this thread. Buffs. You're an 0/3 Zed who wants blue? I'm sorry, but that cdr is not important enough considering there is a high chance you're gonna just feed that buff over to the enemy mid lane. You're an 2/0 Orianna however? I'll probably give that even if I'm some mana hungry bastard like Hecarim.
By all means though, do not just walk over to a buff (unless it's an enemy buff, then I don't care what you do) and think "oh hey I can have this." The only time you can do that is if you're an 17/0 Lucian who has the shoulders of Jesus himself. That or if I'm playing Fiddlesticks or Rammus who don't need red at all. Even then if you're feeding I'll just give it to top. And mid laners; Buy. Some. God. Damn. Mana. Items. That is the point of them. You don't need a 10 minute Zhonya's, so buy a forbidden idle or a chalice. Don't act like the only way you can get mana regen is from blue. Again, same principle as with that Lucian, you're a 14/2 Ahri? Here you go. I'm playing Lee Sin? Here fine I don't need it. But you better not be feeding at least.
Yes, the buffs help everyone. Yes, they should be given to people who use them best. But a 10/1 Kha'Zix can utilize red a lot better than a 2/7 Corki.
And seriously, if you really want/need a buff, just ask ffs. Most junglers who aren't pricks or fed as hell will give you buffs as long as you aren't feeding. It's the whole taking camps like they're there for you, when they are designed to be taken by the person who gets 30 extra gold from them. Taking camps literally gives less gold to the team.