The whole point is to make this process more predictable for travelers. The tech exists, only the political will to force its use is necessary.
They do -- they call it a "full fare ticket" -- airlines bend over backwards to accommodate these full fare fliers, even if it means bumping a paid economy passenger from the flight. Though it's a pretty steep fee -- usually several times more than the restricted fare.
I’ve booked on fully sold flights in a full fare class a few days before and the wait list clears, often in a few hours.