While I agree with your complaint, it's not Apple's fault, and more importantly, I don't think this would work as DSL is tied to a physical location (your house).
If mobile data was charged the same way, what's to stop you and 49 of your friends each chipping in 0.50 a month and sharing the data plan?
Of course fair use would come in to play, but the system would be so open to abuse that the fair usage policy would end up being very low and ruthlessly enforced.
@ the mobile data thing : data caps. I pay for 2 GB of data usage a month. I don't see anything wrong with my friend tossing me $15 and using 1 GB. If 50 people want to split it, I don't see a problem with it (though they probably will).
If mobile data was charged the same way, what's to stop you and 49 of your friends each chipping in 0.50 a month and sharing the data plan?
Of course fair use would come in to play, but the system would be so open to abuse that the fair usage policy would end up being very low and ruthlessly enforced.