Using bad anaologies does not a good argument make!
GM or Ford doesn't have to specify a particular tire brand because they put out a set of specification for correct tire size and type that you do have to adhere to (or you risk voiding your warranty and putting your safety in jeopardy). Tire manufacturers are held ot a certain standard - and if a tire does not meet set standards, they are subject to a Federally-mandated recall and/or serious legal actions both from the government and anyone affected by said sub-spec tires.
I'll give you another more acurate anaology - your shiny new car specifically says that you must use "Premium" grad gasoline (92 Octane rating or higher) to prevent engine damage. But since you know better - that vehicle doesn't really need that expensive gas - so you run down to the local moonshiner and get several cheap gallons of home-made PGA (or maybe you go to the little gas station down the road that has a reputation for cheap gas...) and you fill up with something that your fancy new rig is not designed to run on - and damage the engine... because you wanted to save a buck.
Car companies don't stipulate a brand because all gasoline sold in the US is suppose to be accurately graded, and meet certain minimum requirements.
Apple sells an expensive set of devices. And over the years, Apple has licensed the logo and names of their products to many 3rd party makers, as well as provided "certification" for those accessories for the sake of providing a consistent and reliable user experience for their customers. In the process, they generate a realtively small additional revenue stream. If you use a genuine "certified" accessory, regardless of who made it - and it damages your iDevice - there is heck to pay... Same device damaged by a non-certified accessory - good luck.
One common stipulation on licensing and "certification", is that there is some sway held that if there is a problem, there is a chain of accountability. Buy a cheap knock-off - who are they accountable to? Their Chi-Com owners who don't mind breaking copyright laws, trademark laws, and patents?
I too would rather pay $2 for a charging/data cable than $15-20. And MAYBE I could get lucky and get one that is cobbled together and overrides the safeguards Apple is now including in the iOS. But what happens if/when that cable shorts out or comes apart IN my iPhone? Who do I call? Apple? Yeah - right. They don't (and shouldn't) bear any responsibility. Yet people have done that very thing - filing lawsuits against Apple when they have used junk (and non-licensed/certified) cables, chargers, and other accessories. While Apple typically wins (or gets the case tossed out - because their licensing and instructions clearly warn you against such things), it still costs them for lawyers and court costs.
Further - While Apple could use a parts-bin connector (like microUSB), Apple paid engineers to develope thier generally proprietary connectors - to meet the needs Apple believes they have.
Of course - I just cannot help but shrug my shoulders - when people who purchase what is generally considered a "premium" brand, then spit and complain when they cannot buy cheap, imported, often sub-standard parts for said devices.
Go buy you a $140K sportscar, then complain when there are only a couple of tire makers that make the tires that are correct for that car.... and they cost over $500 each... But you found on eBay some tires, drop shipped with free shipping from Hong Kong for $25 each... And be sure you get REALLY mad at the maker of your sportscar when you get those tires mounted and the first corner you go around, a tire blows and you total out your ride... Be sure to sue that car maker. Yes, they specified a specific kind of tire - with limited availability... but you saved $475 per tire. It is still thier fault the car was wrecked... Oh - and that HK company that shipped you those great tires... good luck holding them accountable for ANYTHING...