So they make a cheaper version, with lower margins, but they deliberately cheapen the experience so that those who can afford the "luxury" version don't buy the "cheap" version instead.
In any case, it shouldn't change anything for the end user, hardware or software, you pay a premium for premium features. And even if it involves actual hardware, it will cost you a lot more than what the part is worth. That's how manufacturers target both the premium and budget market with the same product. I think it benefits most people in the end, especially on the "cheap" side since people can get something they wouldn't be able to afford at all otherwise, at the cost of a bit of luxury.
Now, you can get smart, buy the cheap version and hack the software, or install much cheaper third party hardware. Same idea as ink refills for printers, or ad-blocking ad-supported websites. Often, that's you right, but don't expect the manufacturer to play along, you are on your own.
Because that's not how business works, whether cars, computers, or any other widget. The cost of manufacturing is only tangentially related to the retail value.
Your examples, while contrived, could easily work the same way. As long as the customer knows what they're buying, and there are other choices on the market, then we will find out pretty quickly how valuable a non-binary volume knob is.
You may not want to know the answer to that one, if you pay much attention to airline ticket pricing and consumer behavior.
Welcome to capitalism, it seems you are new here.
> Why charge your customers extra for something that costs you literally nothing extra?
Because (1) you can, and (2) it maximizes profit.
> Why not do the same for everything?
Because of estimates about what people will accept not having in the base model and what some will be willing yo pay extra for. Why do you think there would be some other principal at work here?
If it's that cheap then it should just always be included, period. Otherwise it's just transparent greed. Why charge your customers extra for something that costs you literally nothing extra? Why not do the same for everything? The radio volume knob is software-locked and it's either at 100% or off, unless you pay extra to unlock it. The entertainment system will play ads continuously while the car is running unless you pay extra for the no-ads version. When you unlock the doors they will stay locked for five more minutes unless you pay extra for the Instant Unlock feature.