Because the UI is where installation paths are set, installing with /Quiet doesn't work and results in data being installed in the drive root (https://jira.sil.org/browse/LT-20524, https://jira.sil.org/browse/LT-20519, https://jira.sil.org/browse/LT-22481).
Workaround: /Passive brings up the UI but requires no user interaction, so it can usually be used in automatic deployments.
Because the UI is where installation paths are set, installing with /Quiet doesn't work and results in data being installed in the drive root (https://jira.sil.org/browse/LT-20524, https://jira.sil.org/browse/LT-20519, https://jira.sil.org/browse/LT-22481).
Workaround: /Passive brings up the UI but requires no user interaction, so it can usually be used in automatic deployments.