You can still buy new cables that fit the first iPhone today but you can’t buy a new iPhone that fits the 30pin charging dock in old cars.

The main difference though is that you’d expect a device like an iPhone or iPad to last a maximum of about 3 to 5 years while you’d expect a car to last 10 to 25 years. Accordingly it would be wise to use future proof parts, not proprietary parts that go out of style every few years.