Why doesn't AT&T charge the same rates for U-Verse voice as it does for regular landline service?

We have two phone lines in our house, a U Verse phone and a regular copper wire phone line. We decided to keep one regular landline in case of emergencies like power outages lasting for more than just a few hours, which we seem to have one every year in my area.

U Verse voice is cheaper if you are a heavy caller and want Caller ID, call waiting, etc. But if you just want basic service, the regular landline is much cheaper. Also, if you are on public aid you can get a discount with the regular landline but not U Verse.

The cheapest UVerse plan ($24.99) includes 200 minutes of outbound calls. Local calls count against your 200 minutes. But on a regular AT&T landline the cheapest plan ($11.40) includes 30 local phone calls (no matter how long you talk) and unlimited local calling is ($17.37).

So, on a regular landline I can make a local call (within 15 miles of my house according to AT&T) and talk as long as I want and it counts as one phone call or unit and I still can make 29 more calls. But with the basic Uverse package, I could use up all of my 200 minutes on a couple of long phone calls, even if they are local.

So why doesn't AT&T offer a rock bottom U-Verse phone plan like it does with regular landlines? And I noticed that there are constant rate increases on U Verse whereas our landline bill has only gone up a few cents per year. It seems U Verse voice should be dirt cheap because there is no separate infrastructure. It goes through the internet.