Zaheer unlocked flight by circumstance:
Zaheer happened to be at the right place at the right time when he gained the ability of true flight.
If P'Li wasn't killed then and there OR he didn't witness it physically (I imagine watching someone you love die in person is far worse then learning it through a secondary source?)
There's a chance he might not have unlocked flight, or he may have unlocked the ability later in his life and chose to let go of his feelings for his girlfriend while she's still alive?
Guru Laghima inventing / unlocking the technique was inevitable because he lived during a time when the four nations were at peace with each other so there would have been far less violence, murder and hatred - not saying it's impossible but I find it hardly unlikely he unlocked it the same way Zaheer did after witnessing a traumatic event.
Rather Laghima chose to untether himself from earthly attachments by choice.
Sorry if what I'm saying is hard to understand, just a thought I had.
In no way am I trying to take away from the awesome character Zaheer is, just a thought I had recently.
Anyone else feel the same way?
For all my Avatar (Korra) fans