Part of the problem - for me, at least - is that they never address anything specifically apart from her killing Vince. Her gleeful killing that we saw - even though the team is probably ignorant of most if it, the fact that she had a hand in Oliver's son losing his mother, that she had a hand in Oliver getting impeached, that she tried to kill pretty much all of them at some point gets swept under the rug because she says she wants to be a better person. I do believe that Felicity is more apt to forgive Laurel because she's made gestures of good faith in terms of helping get Oliver out of prison, but their budding friendship would be more believable if these wrongs were directly addressed. And it would make for a more meaningful ~redemption arc for this Laurel, who for the most part hasn't had to face a single repercussion from anything she's done apart from Dinah being mad at her for a little while.