because the iPad is twice the price?
at the level of scale you mentioned, price is obviously a factor even if it is not a consideration.
as someone else mentioned it really depends on what you and your users expect out of the device.
if the plan is to "create" content, then an iPad has limitations.
if the plan is to "consume" content, then the Chromebook must have limiations (fewer apps?)
I am not saying that user desire isnt an important consideration, but my guess is that we can agree it isn't the only consideration.
Why buy a computer limited to something that an iPad can do plus worlds more?