I don't agree with the bill, but there is a difference to the third-parties.
Firstly, everyone talks louder on the phone. They don't realize it and deny it left-and-right, but they do. Add to that, they will be compensating for the engine noise so it's going to be a lot of "can you hear me, what about now, is that better" So you have increased volume.
Second, you have the issue of "half a conversation" messing with your brain. Hearing another conversation isn't so bad, hearing only HALF the conversation (the guy on the phone) and your brain tries to piece together w t h they're talking about or what the person on the other-end-of-the-phone is saying. It's an automatic thing, so it adds to the annoyance.
Lastly, not too many people talk to their strangers / neighbors for more than a few minutes. Sure people talk, but for the most part people just want to veg out and rest / read / watch the movie / etc. Bring in the phones, and LOTS of people will be talking.
Personally I'm fine with the way planes have been... the talking is at a minimum so I can at least try to get some rest. Instead now you will have people going on and on about mundane stuff.
At least... hopefully the teens and younger will be Texting instead of calling... so I don't have to hear all of the "Oh My Gawd did you see what she was wearing" BS.