A car is no longer just a mean of transportation. It's getting smarter and more personal. A smart autonomous car which can take its owner everywhere without a driver is the future. For example, an apple car that connect to apple watch, which know the owner's health, can take the owner to the hospital in case it detect illness. You don't know what a smart car can do until they show you, just like you didn't know what a smart phone was capable of until Apple shows us.
Wireless router, monitors,... are old stuffs. There are others who can do these better than Apple. These are not Apple's core business anymore. And it takes a lot of effort to enter and lead an existing market.
In order to lead the world and open new chapter, Apple need to enter another new market first, just like it did with the iPod, iPhone, Apple Watch, and iPad. There's a lot of risk in new market, but the opportunity is high.
Microsoft and Google are also researching the autonomous vehicles market (Google is doing it). If Apple doesn't do it, Apple will fall behind once Microsoft and Google make their own autonomous car or cooperate with an auto manufacturer.
The autonomous vehicle involves AI, which is Apple's focus now. Apple has been working hard on AI lately, so definitely it needs to at least own an autonomous vehicles software.
The issue is, that car manufacturers have shown that they like to control the infotainment experience. Working with Apple is not going to allow them the same degree of control, as Apple itself is extremely controlling with the UI, something iOS & MacOS users have experienced over the years.
Apple may just choose to develop the core technologies behind AI driving, but they should not be getting into the whole vehicle infotainment business.