How the Pros Package: Better Packages' Electric Water-Activated Tape Dispenser - Core77 (To be clear, the tape is what's water-activated, not the dispenser.).
Folks in packaging facilities are more likely to use machines like the Better Pack 555eS, an electric water-activated tape dispenser.
The operator punches in the length of the seam to be sealed, and the machine then spits out a slightly longer strip of "water-activated"-i.e. gummed-tape that forms an actual chemical bond with the cardboard.