It would be nice were that actually the case. However, in practice, I tend to find that doing most things just using voice with my hands on the wheel and eyes on the road ends up being a really frustrating experience. This isn't a particular knock on Siri specifically. I'm pretty sure I'd find Google or Alexa similarly annoying in the same context. As someone says up-thread, Alexa at home is fine for a few formulaic things that I know the incantation for and pretty useless for everything else.

I'm not a big user of Siri, but I've had better luck than you describe. Siri will reliably play songs and podcasts I request; read out text messages; transcribe my response to text messages; and find directions to places. This is about as much as I really want.

I find podcasts and playlists pretty frustrating generally. But then I tend to want to listen to something fairly specific as opposed to more or less whatever as background; I've never been a big radio listener. I have used it for texts but that's very uncommon and directions can be hit and miss to make changes on the fly. It's definitely better than nothing but it's a far cru from a passenger doing that sort of thing for you.

I have the same use case but with very different results. “hotwords play my playlist foo” works for many values of foo with both google assistant and Siri. Ditto mapping, ditto sending texts.

Do you have an uncommon accent?