The issue is that to move 80x24 dots independently you need 80*24 physical actuators (or an enormous mechanical multiplexer), which is very expensive. Industria

The issue is that to move 80x24 dots independently you need 80*24 physical actuators (or an enormous mechanical multiplexer), which is very expensive. Industrial looms and knitting machines have that but nothing much else does. However, the technology to solve computer braille without needing width*height mechanical actuators actually exists - the fluidistor, or liquid transistor - but is only just now getting serious development, and it's mostly in haptic feedback labs.