i've also owned two keyless cars back to back with slightly different interfaces (two different german manufacturers, in my case) and here are my thoughts, mostly i completely agree with you:
1. touch-handle to unlock is awesome and useful
2. touch-handle to lock is worse than useless. keep this on the fob and on the interior. nobody reaches for the exterior handle when they're walking away from the car.
3. the touch shouldn't be too sensitive, and should only be on the inside of the door handle (or under the door handle, whatever the layout is) - my
4. there should be a delay of about 500ms i.e. touch it for half a second before it unlocks.
5. no button, like you mentioned
Mobile OS designs have little or no contextual awareness or proximity sensitivity, and GPS is too inaccurate to solve that problem.
It wouldn't be rocket science to add a layer that worked out whether you were walking towards or away from some specific hardware reference transceiver, checked some credentials, and responded with some action.
So - car "keys", hotel room "keys", house "keys", house lights, virtual boarding passes and other travel tickets, etc.
Watch is supposed to do some of this but the UIKit in iOS wasn't really designed for this kind of interaction. So the 'wave your watch around to unlock your room' idea still isn't as streamlined as it could be. NFC/RFID may not be the right technology for this.
It's a good bet that Apple and Google have either worked this out already or will work it out very soon. Disney already have.
It's true that current app UIs are non-ideal. But apps are a transitional solution, and I don't expect them to be around in their current form for more than another few years at most.
1. touch-handle to unlock is awesome and useful 2. touch-handle to lock is worse than useless. keep this on the fob and on the interior. nobody reaches for the exterior handle when they're walking away from the car. 3. the touch shouldn't be too sensitive, and should only be on the inside of the door handle (or under the door handle, whatever the layout is) - my 4. there should be a delay of about 500ms i.e. touch it for half a second before it unlocks. 5. no button, like you mentioned