In large part because v4 drivers required re-architecting their drivers. While many manufacturers made unique drivers for many printers or printer families, the

In large part because v4 drivers required re-architecting their drivers. While many manufacturers made unique drivers for many printers or printer families, they all likely built on a shared framework and were not entirely novel. V4 drivers also tended to be buggier and had more problems for administrators until Windows 7.