Preference is subjective. I hate touch screens in cars that so anything but provide a screen for my phone, others love them. Should we ban touch screen controls because of my preference? I like to have a curated app store for my phone and not have a free-for-all with multiple stores of varying quality where I need to set up a new store just to use a popular app. So I can buy an iphone and people who have a different preference can buy an Android phone. If consumers actually cared that much they'd just avoid iOS. It's the magic of the market. Let's have consumers put their money where their mouth is! Stated preference and revealed preference often differ for a reason.
Your cars touchscreen is not a marketplace. The M in DMA is for markets, which is what the regulation targets. Now if your car manufacturer sold the car and someone else sold the touchscreen then you could talk about this but as it stands its a false equivalence.
Apple has a market within iOS over which it can arbitrarily enforce anti-competitive rules, the EU regulates this type of behaviour.
Sure, just one person's consumer choice to curb anti-competitive behavior which is artificially raising prices for everyone and restricting innovation. Among other fringe choices like having electrical appliances that don't kill us, paint that doesn't cause brain damage, cars that don't poison our air, and rivers that aren't full of toxic chemicals.
Mobile phones have had one of the most rapid price plummets and feature additions in history. The only thing stopping another competitor is the fact that it's so hard to compete with them, because they're incredible value for money and there isn't a market being gouged that can be un-gouged.
You're still looking at this from a perspective that's completely irrelevant to this entire legislation. In very simple terms if my business needs to reach people who happen to use iOS and Android devices, and the only way to do that properly is using a native app, then I need to go through Apple and Google because that's where all of my potential customers are.
That puts Apple and Google into a gatekeeping position and allows them to dictate unfair terms because together they control access to what, 99% or more of the consumer market? These unfair terms trickle down to all of us and we end up paying more and have less choice than we would in a transparent, regulated market.
That's what the DMA is concerned with, not some fantasy about feasibility of creating a competitor to Android or iOS, or ease of switching between them which is completely besides the point.
Sane societies recognize the problem and regulate it out of existence.