The customer has no idea whatsoever what he paid for the phone, while Apple and the carrier both know exactly what he paid for it.
And there's a very good reason for this.
That the customer is even lead to believe that the paid only $199 is a joke - about which both Apple and carrier laughed for years.
The customer very easily can compute their own anticipated total cost of ownership for the phone: The up-front price, plus the monthly service fees * the number of months the customer maintains a service contract, plus any buyout fee if the customer ends the service contract earlier than he might have agreed to.
It really doesn't matter what portion of this total cost ends up in Apple's hands, and how much of it ends up going to the carrier. What matters to the customer, is the total amount of dollars that leaves the customer's wallet.
If the customer chooses to go for the "subsidized" phone, agreeing to a 24 month service contract, then their total cost of ownership can be easily computed to be one of two formulae: (Limiting our discussion to AT&T in the USA for the moment, because that's the country this thread is talking about...)
1) If the customer maintains the service contract for the full 24 months (assuming a typical price plan), the TCO is $200 + ($70 * 24) = $1900. Every customer can predict this very easily.
2) If the customer chooses to terminate early, after only N months, the TCO = $200 + (70 * N) + (325 * (24 - N)). Again, this is very easy to work out if the customer knows ahead of time that they'll need to cancel their service. If the customer doesn't know that they'll need to end their service early, then they'd be better off assuming they'll need to pay the full $1900 computed above.
Similarly, if the customer plans on buying the unlocked iPhone, and use it on AT&T (because that's the only carrier in the USA with the technology and frequency bands capable of using it to its fullest extent), it is very easy to work out what their TCO will be. It will be:
$660 + (70 * N)
Now, if they choose to only use their phone for 1 month and then give it up, then their total cost of ownership for "subsidized" phone would be (200 + 70 + 315 =)$585. For the "unsubsidized" phone, their TCO would be (660 + 70 =)$730.
Clearly, they're better off going for the "subsidized" option. The value proposition only gets better for the "subsidized" option the longer they remain on the contract.
The value for the "unlocked" option only really comes into play with a customer who knows that they need to
switch carriers while keeping the same phone. And in the USA, that effectively means that they know that they'll need to leave the country sometime soon.
Now, any customer who decided it would be a good idea to buy the "unsubsidized" phone through AT&T instead of buying it direct from Apple (in which case it's still locked to AT&T), was a complete fool. Because in that case they'd get all the price disadvantages of not accepting the subsidy, but without any of the convenience benefits of being able to connect the phone to another telco.