I've done a lot of reading on this matter, and it's generally accepted to be battery saving limitations from phone/mobile OS makers rather than poor engineering

I've done a lot of reading on this matter, and it's generally accepted to be battery saving limitations from phone/mobile OS makers rather than poor engineering on the car systems. That said, Teslas come with keycards designed to slot into a wallet, there's no smartphone requirement at all. It's actually less smartphone dependent than other car manufacturers, who lean on Carplay/Android Auto for rich features.