SAE levels 2-5 are all about liability. I'm not sure why that is hard to comprehend. It has zero to do with functionality, although the assumption would generally be that they would coincide as systems increase.
Level 2 means 2 driver assists features working together. This is steering and braking/acceleration. Guess what, that is 100% of what we do when we are driving.
Even if FSD beta is 99.99999% reliable everywhere, it's level 2 if we have the liability. (We are the driver) if Elon says they'll take responsibility in certain situations, but we have to be ready to take over in certain situations, then it becomes level 3. If we can engage the system in certain scenarios and not worry about paying attention, then it becomes level 4. If we never have to pay attention and can engage it anywhere a car would be driven, then it's Level 5.
SAE levels 2-5 have nothing to do with functionality, it's all about liability.
My question on the FSD trial for new customers is that if you start the trial right away before "FSD Beta" is released, it's kind of pointless, but if you allow them as part of the "FSD Beta" program, then you'll have all of us that paid for FSD pissed off. I haven't seen any guidance on how they are rolling this out yet, but I can see this being messy.