Back in the old days, the primary users of many mainframe UIs were the data entry team (almost universally female).
Sitting in large offices with rows of desks and a huge clock on the front wall, they weren't interacting with customers, they were transcribing from sales sheets, order forms, application forms, etc. prepared by someone else.
There was no great need for user friendliness, because the only users were in house, and they performed the same data entry hundreds of times every day.
The only need was for speed.
The arrival of the PC started changing everything, as people got familiar with the mouse and GUI.
Somehow mouse-based GUIs became the default for everything, which made a lot of sense as at the same time data entry was pushed out to the users themselves and intermediary data entry staff disappeared.
But if you want a fast, simple way to quickly perform common transactions even on very small screens, old school TUIs have a lot to learn from.