A lot of people are eligible for carrier subsidized upgrades every few years as well. When I did this I could have gotten my SE2 for free from verizon from my plan. I chose to pay like $200 premium to get it with the highest storage sku.
It isn't just verizon either. Here is metropcs offering free iphone 13s for new customers:
They even tell you what the actual rate is in the fine print. It's just priced in: 17.49$ over 36 months comes out to 629$.
>Monthly payments shown are for customers who qualify to pay $0 Down, $17.49/mo. for36months; 0% APR. Retail Price: $629.99