This is not entirely accurate.

There is a tiered guideline that is used to determine whether or not an interlock is required and the length if time from the previous dui is also a factor.

It doesn't matter if the offender has a car or not, if it is ordered that the offender have an interlock installed and an interlock endorsement, they are not allowed to operate the vehicle, regardless of ownership.

Of the offender gets caught driving while under suspension or without an interlock device installed on the vehicle they are operating or without the endorsement, it's mandatory jail time.