It went on into the 90s for general Motors (I work in parts and pull key codes to cut new keys. It comes up). But yeah, I am not familiar with the import brands (well, imported to the US like Honda or VW) doing the different key thing, but wouldn't say for sure as I just don't know

Basically, keys kind of come hand in hand with the invention of the starter motor.

Prior to that, you had cranks on the front of the car. On Dodge vehicles they were colloquially known as wrist breakers due to the quirks of their operation.

As for separate door and ignition keys... that is exceedingly uncommon these days, but seems, to my knowledge, to be a quirk of the Detroit Big 3. These days, basically every vehicle is keyed the same door and ignition.