I'm assuming that because I've never seen anyone trying to solve math problems while driving their car through an obstacle course(or anywhere else for that matter) and when I do talk on my phone hands free, I stop listening to the person when I need to pay attention to the road. The Mythbuster's driving tests prove that you can't solidly focus on the road and solidly focus on driving simultaneously, while an interesting if not unexpected result, this doesn't actually test what people actually do and if you want to prove something is dangerous you need to actually test it.
Hands free texting may be massively dangerous, it may not, the test they did doesn't prove one way or another because it doesn't test hands free texting, it tests a slightly less involved version of hand texting.
In terms of your personal attack on me, I don't text while driving, hands free or otherwise and I wouldn't be dramatically surprised if hands free texting isn't massively safer than non hands free version, I just wish people would actually fucking test the thing they're claiming. Test people driving having ordinary conversations, test people using actual hands free, and in an ideal world actually take the results you get and extrapolate them to real driving conditions(ie, if talking on the phone hands free increases the time before you react by half a second, how often do people actually encounter circumstances where that matters and could those circumstances be dealt with better by maintaining a larger follow distance?). How many deaths does hands free talking on the phone actually cause? From what I can see looking at the road toll statistics there hasn't been any kind of significant upward movement since cell phones became popular, if anything the road toll appears to be going down.
Do I like talking on the phone when I'm driving, yes, yes I do, it makes my boring commutes less boring and allows me to keep in touch with my family that live on the other side of the world(my commute is perfectly timed for calling them). Will I consider reasonable evidence that doing so is significantly increasing my likelihood of endangering myself and/or others? Of course I will, but I won't accept another bogus study where they test circumstances which are different than anything anyone ever does then claim the end of the world based on something they didn't actually test and work to ban yet another thing. The way we're going now they'll have to ban phones, radios and other people from our cars and then we still won't actually react quickly enough, or still won't see the oncoming car, or will go apeshit bored and start daydreaming and become even less safe.