I mean sure, they do this with electrical outlets fine. But that doesn't mean having a dozen or so different outlet standards is the enviable state of affairs.
That's too late to fix.
This currently is not.
We are for some reason, however, voluntarily doing it again.
I am a steadfast engineering internationalist so in practice a single standard is always going to be my bias
It's a bit different from normal electrical outlets though. For DC fast charging, it needs to negotiate exact DC voltages. The dispensers are all designed to operate at a range of DC voltages to match the state of the battery and are constantly adapting to the battery.
In AC charging, the chargers are probably just designed to be way more tolerant of a wide range of input AC voltages.
So in those instances a purely passive adapter works fine. Or probably a cheap-ish retrofit of the outlet in the car since I doubt many cars go on intercontinental voyages very often.
And that's kind of the thing. The extreme majority of cars aren't going to go past their original target market continent. Taking a car from one continent to another often involves a lot of import duties, inspections, regulations modifications, and is generally very expensive.
Meanwhile with regular home devices you usually need to be sure you're supplying the right voltage as most home devices can't deal with other voltages. So adapters are more complicated and improper adapting is disastrous. Lots of things are small enough and unregulated enough to send through the post or carried on an airplane. It's a much more common hassle trying to plug in a shaver when travelling than figuring out what to do with the car you packed in your carryon.
Also, with everyone on the same standard, all companies have an incentive to optimize their hardware to accomodatte it.
It might not be that important short term but it is on the medium to long term to complete a proper transition.