Damage from the bushes- Except Sol?

EDIT: https://www.youtube.com/watch?v=OdZ7lp1GTeU&feature=youtu.be So we made another custom where we displayed a bit of the differences here. Sol is visible during the wind-up of his ult. Anivia's ult becomes visible during Tlord proc- if it's down, you don't get to see it.

I am honestly curious. I'm not asking anything to be 'fixed', buffed or nerfed. I'm just curious as to why Sol can't use bushes effectively due to his stars (his stars do not stealth) but champions like can wind up his Q in a bush (specifically talking about lethality Sion who can half health you from stealth) - you don't know he's there, assuming you didn't ward (and before you answer this question just assume you didn't ward whatever bush he happens to be hiding in). Karma too, can Q+Ult into a bush and you don't know it's there until you walk into it. I also understand Sol's stars are not a wind-up or exploding ability- so they technically hit faster than a Sion. Additionally, I know Sion is not revealed during wind-up because the wind up itself does not do damage. I'm just curious as to why Sol's stars cannot be stealthed - until he damages something. And perhaps a better example than Sion would be Nunu. He can slow you (via ult) while he channels and remain hidden until he's done. Anivia. Can place her ult in a bush - does not reveal even after it does damage to you (sometimes - we did a few test runs and it would SOMETIMES reveal if thunderlords was proc'd)(also working on getting video of it, our first custom we exited the game instead of surrendering so it didn't save)

I guess I'm just wondering- why is this not normalized across the board? Either you can or you can't see someone from a bush using or preparing a damaging ability. Sion I get- since it doesn't do damage until it's hit you, but that's the thing....why is Sol visible if he hasn't hit you?