But if you can unlock all the doors from the phone that doesn't seem too different to me than unlocking the doors using the fob, you need to take something out of your pocket either way.
A smart phone is specifically designed to keep your eyes glued to the screen. It wants your undivided attention when in use. That is exactly the wrong tool to be using in a parking garage, where your attention needs to be on your surroundings. A fob can be used without looking at it. A smart phone cannot. For the Model 3 therefore, the keycard, not the phone, needs to be your primary key.
Another option they could do (no idea whether they've done this, but it's just a software update away) is to hold the keycard against the car for a couple seconds to unlock all the doors (the exact equivalent of twist and hold).
YES, this is one I dearly hope they will adopt. I have not seen any evidence of it as yet, but as you say, it is something that should be easily implemented with a bit of software.
I would hope if you pull on any door handle when the phone is very close then it will unlock (this is how most keyless entry systems work). This would be separate from the automatic unlock feature when approaching the car.
Yes, I think this would be acceptable, but only if the car is sensitive to which door the person is standing by. I don't know if the MS/X can do this (anybody know?) In use, you would program the car to not unlock on approach, but only when standing immediately next to a door, and then pushing the handle on that door. So, in Daniel's example, you'd open the passenger side for your girlfriend first by standing next to that door and opening it, then walking to the driver's side and doing the same. (Really, you should be doing this anyway, right?) Only the single door you are standing by would be unlockable (but not unlocked unless touched). That way, if you happen to walk by the passenger door on the way out, the passenger door wouldn't unlock itself. I think the trunk should operate the same. So, if this can be made to work reliably, then I might consider the phone as a primary key.
I'm confused, how could Tesla (or anybody else) have solved the issue of "I want to leave my key (or in this case my 'phone' acting as a key) in my purse, in my car and walk away and have it be locked". The only way to do that would be to have another key. Otherwise you would lock your only key *in* your car? I just can't fathom how anybody can solve that logical problem.
Yes, another key (the keycard, for example, or your phone). And that key would be remembered as the one to unlock the car, not the one that's sitting inside the car. A linked phone could override, of course, since it's either in your possession and presumed safe, or in the car and presumed screen-locked. But that override would need to be explicit, not simply by proximity.