iPhone usage vs any Android phone

I was trying to understand Verizon's thinking behind having special plans for iPhone, but only found articles like this:
"The key detail in this study that drives the average is that, by percentage, nearly twice as many Verizon Wireless smartphone users are consuming 500 megabytes to 1 gigabyte per month compared to AT&T iPhone users,"

So is it a matter of charging more simply because they can?