Hi Korcar, I am sorry you are in this situation and I could see how this is "unfair." You paid for FSD and an upgrade of the computer, as I did as well. At that time we thought that would be all that is needed (and Tesla said or implied as much).
That said more recently Tesla has said that cars with AP2.0 cameras would need camera updates. Tesla did not start shipping AP2.5 until around 7/17. So while your computer was upgraded from AP2.0 to AP3, the cameras were not (because nobody has had that done yet).
Those customers with AP2.5 do have the full color cameras necessary and if they did the AP3 computer upgrade are now getting FSD.
It doesn't help that the camera and computer dates are different and even some newer vehicle got old MCUs. So you may have some cars with AP2.0 cameras with old and new MCUs and AP2.5 cameras with old MCUs. AP2.5 and AP3.0 cameras are the same. Cars that were AP2.5 (new cameras w Nvidia computer) that got the new Tesla computer are now AP3. Things like TeslaFi only report on the computer. So if you had AP2.0 and upgraded the computer, TeslaFi will report it as AP3 but it still has the old non FSD capable camera.
To complicate it further Tesla also shipped AP2.5/3 cameras on S/Xs that had no cabin camera. So across the line up there is a mix of AP2/3 cameras, cabin cameras, and AP2.5/AP3 computers. There is no way (as far as I know) to tell the difference between a car that has AP2 vs AP2.5/3 cameras, except if you have a cabin camera then you do have AP2.5/3 cameras. Even if you have the older computer you may be lucky and have newer cameras (yes that DID happen for a period of time). But if you have the AP3 computer, that does not automatically mean you have AP2.5/3 cameras.
You don't need the cabin camera for FSD. But you do need the Tesla computer (AP3) not Nvidia based (AP2.5) and full color cameras (that started shipping in AP2.5 cars). Somebody can probably make a nice graphic to show all of the dates changes and dependencies
The good news is Tesla will eventually upgrade your AP2.0 cameras, as they did the computer, because you already paid for FSD.
The bad news is you have AP2.0 cameras and not AP2.5/3 cameras (which didn't start shipping until after your car was manufactured).
I think you have some right to be unhappy/upset, but as others have stated your car does not have all the hardware necessary to get FSD Beta.