Those boards are ~$1000 each. High level tournaments use them, but low level tournaments don't unless some rich person has bought the club a bunch. Most tournaments are low level and are designed not to turn a profit: the entry fees either pay for the room rent, or go to the prize winnings: the more people who enter the more prize money there is.

Yeah, the DGT board is perfect for on-the-fly tournament analysis -- but a computer vision tool would be great for times when you don't have access to the/a DGT board or its data

Set one up at the park and get some insight on those hustled blitz games!