The ad says all three, but ads aren't always correct.
I think it's because only Sprint and Verizon will still let you do 2 yr contracts if you're on an older plan. Hence, $200 subsidized - $200 = 'free' (or $1). I don't think AT&T lets you do 2 yr contracts at all anymore.
If you must finance the phone @ full price (with all the current finance plans), you still get the $200 card. Take your pick -- AT&T NEXT, Sprint Easy Pay, or Verizon DPP
Note that depending on your plan, it's actually much cheaper financing the phone @ full price (vs getting a 2 yr contract w/ a subsidized phone) due to the Smartphone Line Access fee, which varies depending on your account type and plan. The cheapest/most economical is if you have the current AT&T Mobile Share Plan (10GB and up) or older Verizon More Everything plan (6GB and up), which puts your SLA @ $15/month for each plan.