With Liquid glAss CarPlay on non touchscreen cars they changed the button colors so that gray is the selected item and blue/green are not selected. Also they changed the back on-screen button to be the default, or sometimes they select the item you want but then a second later change focus to the back button.

When you first use CarPlay there are consent screens so there are definitely people out there who have picked the wrong one.

Technically yes, but most would consider an opt-out some tiny little nearly illegible that confuses the user into allowing it without deselecting. This is a clear choice given to the user. No gimmicky opt-outs.