> A clear outlier case.
Everyone speeds a little when they think it's safe, but some people speed excessively.
This is about making a remedy available to judges, as an alternative to other, less effective, or more draconic (or both less effective and more draconic), forms of punishment.
And judges deal with outlier cases every single day. They job is to look at and weigh all the special cases and considerations, provided by two sides in a dispute, and prescribe one of the many remedies available to them by law.
There's nothing fundamentally immoral, tyrannical, or unfair about requiring an repeat offender who has demonstrated their inability to follow the rules of the road to have a conditional license if they want to keep driving, and there's nothing immoral or unethical about using mechanical mechanisms to enforce those conditions.
Because the alternative is a full revocation (which is catastrophic to the ability to make a living in this country), or prison (which is catastrophic for a whole lot of other reasons). There's a reason that prescribing ignition interlocks for DUIs results in a dramatically lower recividism rate than license suspensions, and a dramatically lower overall social harm than prison.
Locks keep honest people honest, and they put up enough of a hurdle for most less-than-always-honest people to not consistently act like anti-social dipshits. You can circumvent them with effort, but we still use them. They are part of a defense in depth.