(1) astronomers are pretty darn aware of everything going on, and it's really shocking as an astronomer to see these sorts of claims. There have been close collaborations with Space X to try to mitigate some issues, but these are partial mitigations and the most important ones are only planned, not implemented. The "successful" mitigations I think you're referring to is their "DarkSat" coating, which is not actually a successful mitigation. It is still ~2x as bright as the ~maximum level of acceptable brightness for e.g. LSST.

(2) Space-X did not release any details about brightness characteristics, and they themselves claim that they were "surprised" by the brightness. To people that work in space rather routinely, that is staggeringly incompetent.

(3) > why do most not know Starlink was never visible except at dawn or dusk

Near earth object (NEO) detection only happens during these times. NEO includes "asteroids that threaten human life" so I would hope you agree that this is pretty important. Also, depending on latitude and time of year, "dawn or dusk" can constitute your entire observing window. So this doesn't really make things better.

(4) all of these mitigations should be done before companies can start doing ~10,000 satellite launches. The only reason this isn't done is outdated legislation that never conceived of this being possible.