Where did the savings come from? Maybe they were licensing a paid font? I doubt saved them more money than using a free font.

They were licensing Whitney SSm, they switched to a Source Sans derived typeface to save those costs but forked and adjusted it to more closely match Whitney SSm to minimize brand disruption.

In the documentary video, their CCO explained if they used a different existing font they would have had to rework a lot of their media for the different font metrics, while making their own allowed them to have a drop-in replacement.