The main problem you have in this concept is that the big German/Japanese automakers are going solo , each big car "firm" is trying to win by themselves , giving Apple big money for each car sold doesnt seem like what those corpos are trying to do , at least today.
Also take few years back when Tesla just started , I read the SAME exact comments about "how can they compete with 50 years of industry experience" ,and other comments like that , same with Apple building phones to compete with blackberry and Nokia , now days it looks obvious to you and you use Tesla as peak electrical car as your reference , but it wasnt the case back then , give them a chance , and judge accordingly , there is no reason they cant build a good car , its not THAT complicated , its very streamlined these days and can be done on an automated production line unlike the good old days where you needed manual workers , getting good car designers is not an issue either and Apple shouldnt have problem attracting talent.
regarding issues with scale (wont have super charger network) - Apple are churning out 250 million phones in the biggest (by far) logistic operation in the tech world , on a yearly basis with no hiccups with great QA , they will know how to setup the manufacturing lines for whatever they decide to build , no worries there.
The only thing that might hamper them is the price , if they over engineer the car to a point they need to price it so high that avg joe cant buy it , it will be tricky , but they will probably go the homepod way , highend first, low end later.