There's a substitue teacher today!!!!

I recently was performing my duty as department chair for special education and used my planning periods to conduct some walk-thru's on co-teaching.  I attempted to observe three 8th grade team taught classes, two 7th grade and two 6th grade classrooms.  Out of all of these classes, I was able to observe one 6th grade co-taught social studies class with both the special and general education teachers present.  The instruction in this class was very good, but not all of the students were engaged.  In all of the other classrooms, the general education teacher was absent with substitute teachers (seriously) and the special education decided to pull their children out into a small group.  Now, what's wrong with this picture????  One, the students are out of placement based on their IEP and two, what about the general education students?  I was so frustrated with the behavior of the special education teachers.  It's enough for the general education teacher to be absent, but for the special education teacher to leave the assigned classroom to me is despicable.  In my opinion, this is the perfect opportunity for the special education teacher to build a rapport, help keep order in the class and simply teach the class.  Does anyone else experience this at their school?  How do we change the culture of there's a substitute?  How and when does administration hold all teachers accountable for performing their duties?  Please help!!!