Aside from the fact that I find it extremely offensive that someone on probation can (or could) require the State to chase their sorry butt down for not complying with their probation conditions.

When did "due diligence" go away as an issue in probation revocations?

I believe it was amended in 2003.

HB 1634, 78th Leg. Regular Session

This issue is covered in the chapter on revocations in The Perfect Plea.