The reason for this is that technical violations of probation are often not serious enough to warrant revoking a person’s probation and putting them back in prison. In such cases, it makes more sense, both financially for the state and in terms of the probationer’s welfare, to keep the probationer in the community.
Technical violations of probation are similar to status offenses among juveniles. In other words, these are actions that are only illegal because of the person’s status as a probationer (or as a juvenile in the case of status offenses). In the case of probation, these could be offenses such as missing a visit to one’s probation officer, failing to be home before a set curfew, or using alcohol. These are actions (or failures) that are not serious and would not have been illegal were it not for the fact that the person was on probation.
When a probationer commits such an offense, they are often not sent back to prison. Returning them to prison would seem like a very harsh punishment for something that is, in essence, a minor offense. This is one reason why probation is often not revoked for technical violations unless there is a clear and persistent pattern of such violations. Revoking probation seems like a disproportionate punishment.
In addition to being unfair, revoking probation would harm both the offender and society. It would harm the offender by putting them back in prison, making it harder for them to maintain family ties, to keep jobs, and to ever return to being productive members of society. It would also, however, hurt society. It costs much more to keep an inmate in prison than to have that person out on probation. Therefore, it does not make sense to incarcerate someone for a minor technical violation so long as the violation seems to be an unusual occurrence.