I disagree with the 99% estimate, I too take the same approach, and recommend the same to those who will listen. I would venture that number to be at least 80%
Yeah, no!
I think your intuitive judgement failed you here
Young kids seem to install apps all the time, but parents quickly learn not to let them spend any money on in app purchasing.
Those don't matter much for the concerns of TFA, as they're unlikely to use some new fangled web app either...