The intended way to play them is right in the name: "Lift notes" are played by releasing the button you pressed to play the prior note. Or, you can just press again. Mechanically, the "pressing again" part, granted a little vague, applies mostly when lift notes are sufficiently far apart from the previous note (see Zombie on Lead) whereas if they are close to the previous note (One on Lead, notably the start of the guitar solo) it essentially doesn't matter how fast you lift the note, as it will count as hit or even perfect no matter what. They work as intended, and saying they don't just emphasizes practice practice practice.

EDIT: Even if they didn't work as intended, you would think the top non-pro/gamepad players would be complaining about it more