Well there are a few things wrong this this...
1) All indications are that the target date for the Evo 3D was in fact June 3rd. But it got delayed during the FCC testing process. It didn't finally get approved by the FCC until late May, so that ruled out an early June release. Everyone speculating on the release date being early June was also speculating that the device had already cleared the FCC and we just didn't know it yet. The reality is the phone it had not cleared the FCC yet, and took a lot longer than usual to clear the FCC.
2) The Evo 4G release date was very well publicized. Much more so than this Evo 3D. You may not have heard about it, but millions of others did. That's why it sold out on the day it was released and stayed sold out for several months. There were lines at all the Sprint stores, Best Buy, and Radio Shack on the day the Evo 4G was released. No, it wasn't on the same level as the iPhone. But this is Sprint we're talking about, not Apple. No phone has ever been publicized and marketed as much as the iPhone. It was Sprint's best selling phone of all time though, and it did have a very high exposure. I have no idea how you didn't hear a lot about the Evo 4G release date, but it was actually pretty highly marketed.