No, they can’t.
The Model X has more horsepower than the Model Y (or the BEV equivalent, if that’s not the right term). Not because of its software, but because it has bigger, more powerful motors. If you want more horsepower, you have to buy a physically different model. Same with mpge - the Model Y gets better mileage than the Model X, because it is a smaller and lighter vehicle.
It’s the same thing as with ICE’s. If two BEV customers want different horsepower or MPG, they have to buy cars with different motors and different sizes. And as with ICE’s, those choices will affect the cost of the vehicle - so people with different budgets will still face choices between different physical models.
You can artificially limit the capabilities of a vehicle with software - you could go to the expense of putting in a Model X motor in a Model Y and use software to make the motor run at less than full capacity. But there’s no reason to do that except in very unusual situations. Tesla did that for a while when it wanted to offer different battery ranges without actually changing the battery packs, but it doesn’t make much sense in the long term to bear the cost of installing battery capacity that’s not going to be used. Which is why Tesla phased that practice out.
“For most transport there is a form factor that is most efficient and dominates most uses. You can see that from bicycles to golf carts to big rigs.”
There’s a baffling amount of diversity in model styles in bicycles. And golf carts, and even big rigs. And, as Goofy pointed out, in privately owned aircraft (big difference between a Piper Archer prop plane and a Gulfstream G6 jet). At least as much as in cars, which today have a lot of the same “form factor” (four wheels, two axles, steering wheel, etc.) but a broad diversity of models. There tons of different models because people have different needs, style preferences, and budgets.
Yeah - it changed thirty or forty years ago. And the diversity of models never went away. Nor was there a paucity of different models in countries and cultures that didn’t have the same romanticism of the automobile as the U.S. - it’s not like you see a homogeneous collection of undifferentiated cubes when you look at the streets of Europe, either.