Parts were mostly never standardized. The difference is when a production run ends they would sell all the tooling to a third party that makes parts under their own name. (and even before production ends parts that break often are worth duplicating). With computers when the production run of the LCD, CPU, ... ends nobody is making more. Even if you could get the software to install, nobody makes the computer at all at any price.
Fair, standardized probably isn’t the right term. Maybe common usage is a better term? I saw a video where someone was modifying a Dodge Viper and found that it used a Ford branded control switch or relay, not even the same company! Although that is a bit of an outlier.
Other parts were sourced from outside suppliers, which also supplied the same or similar parts to other automakers. Some of them were direct replacements, some were easily modified to work, and some could be robbed for components to refurbish your old part.
