That title may sound a bit "fanboyish", but unfortunately, for Android Auto it is 100% true. You see, every Android manufacturer handles USB connections a bit differently. For example on my Nexus 6P, all I need to do is plug it in and it starts working perfectly fine with Android Auto. The same goes for the Moto G4 and Moto G4 Plus. But when it comes to the LG G5, sometimes it works, sometimes it doesn't. Sometimes it recognizes the device for a second, then acts like it isn't plugged in. Every so often I have to change the USB mode on the LG G5, which isn't a good user experience at all.
By the way, we can't forget to mention the fact that the Galaxy S7 Edge on Verizon did not work with Android Auto at all since launch (this has since been fixed). Through our experience, with the many, many different smartphones that come across our desk, it appears that those running stock Android not only make it easier to plug in and get Android Auto going, but they also provide a better experience overall. The Nexus 6P doesn't lag or stutter at all in Android Auto. However, the LG G5 does, from time to time. It's something you'd expect Google and the manufacturers to fix, especially now that Android Auto has been available to consumers for over a year.
It's unfortunate, but it does look to be the case. A smartphone running stock Android provides the best experience with Android Auto. Could this be Google's way of selling more Nexus devices? Maybe. But probably not. For many, the extra annoyances that comes with other smartphones and Android Auto, won't be a big deal. After all, you likely aren't using Android Auto every single time you jump in the car. But the annoyances do still exist, and it's something that Google needs to work with their partners to fix. It seems that Samsung smartphones have the roughest time with Android Auto, which is a bit odd since they sell the most Android phones out of all the Android manufacturers out there.