There's a few things to unpack here. One is the perception of the iPhone. Eg here's a quote from PC Magazine I saved when it came out: "Poor business e2mail and PIM connectivity. Bad audio quality on phone calls. Tons of GSM buzz on nearby speakers. Virtual keyboard hard to type on. No phone functionality with iPod speaker docks. It’s the best portable media player ever. It’s possibly the most fun we’ve ever had with a handheld device. It browses the Web like a champ. But poor phone call performance and missing messaging options make us unwilling to recommend it as a phone." There are similar other criticisms. It was not part of the category of smartphones at the time as seen by the people using them.

The early criticisms about Tesla's build quality and a lot of the arguments about a battery not being good enough seem to follow a similar argument. Is the original Model S as good as a top of the line gas car at the time? By most metrics used at the time, no. The criticisms in the peer comment by lbsnake7 are similar - those are legacy metrics of a car. However it did find a customer base that valued what it offered, bad seats and poor panel gaps and all (just like the GSM buzz and non-replaceable battery).

As far as the timeline, the slowness has surprised me a bit but I think comes down to a couple of things. One is the turn over time of getting a new phone vs a new car. Cars are much slower. And another (which might be related) is the price point of cars being orders of magnitude larger than phones. And finally, it's taken a good while for Tesla to ramp - it's been supply constrained forever (although there might be signs of that shifting).