No, I purchased one of these at WalMart:

Note, that's not my photo -- I googled it -- but it is identical to the package I purchased.  Not a smartphone, and the ONLY mention of the $10 included airtime is what's written on the packaging. 

I didn't understand the rest of what you said about merchant accounts and plateaus (this is ordinary, consumer-grade prepaid), but I did port a number in, which took two days.  Are you saying that there was some unwritten (and unstated) stipulation that I purchase airtime before the $10 was added to the account? I was hoping to try out the service using the $10 airtime to allow me to get a sense of what it was like without any additional costs.  I guess that hope was misplaced.

As it turns out, after paying $15 and emailing customer service, someone added the $10 to my account.