Repricing a purchased airline ticket

Factual Questions
1

I was doublechecking on United’s website for my flight I was taking for Christmas. Turned out that they had an option where I could reprice my flight to see if the fare had gone down. So I did and I am getting a voucher for $32.

My questions:

  1. Why would the airline allow this?
  2. Was this something they didn’t publicize?
2

Can’t answer your questions, but where on their website is this feature?

3

If you have an existing reservation on United.com, you pull up the itinerary and there should be options for changing the ticket at the bottom.