Some do, but what you should understand is that this money was designated as bait, so its only purpose in the 6 months or so that its been in the vault or drawer is to be that bait in case of a robbery. The idea behind the dye pack is that its ink is permanent which makes catching a robber incredibly easy. Essentially, follow the guy with the purple face or hands. Many banks do not use dye packs, but they may use some other form of security measure. It's all about the bank's preference.