i see where you're coming from, but i don't really agree that changing a station isn't as distracting as texting.
if i text and drive, i swype a word, look up to assess my surroundings, swype another, reassess my surroundings, swype my last word and then continue driving.
when i use my radio i have to extend my hand out farther from the wheel than where my hand would be if i were looking at my phone (right beside the wheel). this would increase the time it takes to get my hand back to the wheel in case of an emergency. and of course, whereas my peripheral vision would be on the road, because i hold my phone close to eye level, if i were looking at the radio my peripheral vision would become useless because my radio deck is far below the windshield. and then you've got to factor in the whole picking a station ordeal which would take much much more time than to simply swype a less-than-sentence-long text.
i think also that it may vary from person to person. i would like to believe most people have enough common sense to not distract themselves with ANYTHING at all when they're in heavy traffic on a windy road.
but yeah, this is just my opinion and i'm probably wrong.
Are you honestly saying that texting is safer than changing the radio, or are you just playing devil's advocate? Because surely you don't actually believe that.
Most factory head units have big, fluffy buttons for people to push without even looking. I have 6; I can run through all 6 presets without ever taking my eyes off the road. I can very easily switch to the next set of presets without ever taking my eyes off the road. 90% of factory head units don't tell you anything useful on the LCD screen; if you set up your radio presets to your favorite stations, you don't ever need to look at the LCD screen. And finally, you're changing songs, not thinking about what you want to say to the recipient of your text. That takes virtually no mental capacity to decide... "Yes, like song" or "No, change song." You're not having to consider what you want to say, where the buttons are to say it, or trying to comprehend what the response says at 70mph.
What I don't get is why people feel the need to text at all while driving. If you're texting, obviously the person you're texting is busy (otherwise you could call them). You're driving, so I'd say you're busy too. If you're both busy, what is SO important that you need to endanger others while you text them? And if it IS that important, maybe you should stop somewhere and call / text and work out whatever it is you need to work out. And if it isn't important, texting back and forth about the hot chick in Biology while piloting a 3-4k machine travelling 70+ miles per hour is just asinine.
To that I would like to see how our state legislators would respond and would love to see the insurance industry respond by raising the premiums of those who text while driving. 
My experience has been that this age group actually prefers to text over talking. I don't get it either, but it is real.