It rarely decides mid because firstly, mid tends to be about who pulls of the better roams. Think, Annie vs Zed. Doesn't matter if Zed gets a kill on Annie if Annie roams bot and gets a double kill. Hell, even better if her AD Carry gets a double because of her roam. It's basically gg after that.
Secondly. Mid lane match-ups are far less interactive due to many of these match-ups being ranged vs ranged. You see the main reason why the 1st kill decides top lane is because many of the top lane match-ups are melee vs melee. This means that whoever gets even the slightest lead can zone his opponent off the wave and deny him xp. He can freeze easily to setup ganks. He can shove to maintain lane priority which allows him to roam/teleport/invade. Without the ability to safely contest waves, you basically lose control of the lane. In a mage vs mage match-up, everyone is ranged. You can kill a Ziggs 4 times, he will still be able to shove you in and poke you out whenever he wants. The Ziggs can no longer out-right hard win the lane but he can still control it as much as he wants which, I would argue, is more important.
Now while Bot lane is more or less ranged into ranged, it operates more similarly to top lane simply because you have no control over what your random SoloQ duo does. If you get killed as the AD Carry in bot lane, you can still control the lane due to being ranged. However, 9 times out of 10, your dumbshit SoloQ support won't understand item advantages and try to force shit repeatedly and pretty soon your entire bot lane has fed all to fuck. This also applies if you're the support playing with a random dumbshit SoloQ AD carry. This is the primary reason I will never main a bot lane role. It frustrates me to see random baddies in SoloQ forcing fights on the enemy when he has a
to the enemy's
.
As for the jungle. Well, it's a little different. The first kill can decide the jungle but for a different reason. It has to do with tempo. You lose tempo as a jungler if you're the first one to die. You will fall behind in camps which means you fall behind in Gold and XP. This subsequently means that you have to spend more time farming which is doubly difficult if you get your camps stolen while you're dead. Now while you're farming the meager offerings in the jungle, the enemy jungler is ganking and getting shit done. Now you can try to match this, but you will be doing this less effectively. His ganks at level 6 will be way more devastating than your ganks at level 4. And good luck if he runs into you trying to sneak dragon while he is 3 levels above you. This is the kinda shit that happens when you fall behind as a jungler.