I am always amazed at the range of responses that come out to threads like this.
To the original question, yes, it does seem like your DH is being over-accomodating. But it sounds like most of the discussions on this happen when he comes home later than you expected, with an overly tired child.
It's probably worth setting up a time for you and your DH to figure out how to deal with this. Maybe on a holiday or Saturday when you're both fresh and able to work through it.
As to what's reasonable? Obviously, this depends on the situation.
I will say that I have a pretty fair amount of experience in talking with teachers/admin people. My kids do have their share of problems, and I don't let them fester. My kids are both middle school aged.
My first approach in this school system (and I thank God for this option!) is to email the applicable teacher/admin person and tell them what I'm concerned about. If I think it's simple, I'll ask for their opinion. If I think it's more involved (or needs 2 or more peoples input) I'll ask for a meeting. I have NEVER had a teacher who didn't answer me within a day or two at the most.
Now I had one specific issue this year that I did things a little differently. When I spoke with DS at the end of the school day (I always call to check in that they got home), he told me that he had a really bad day because two boys were bullying him, had thrown his book in the trash, and actually threatened him in his Math class. He said that the teacher had heard it. This boy lives in our neighborhood, and the threat was specifically that he was coming over to our house to get him.
I tried calling the teacher (they all have an extension listed on their web page), and she wasn't there. I left a message with my work, cell, and home phone. I then sent an email explaining what DS had told me, and told her I was concerned.
The next morning, I took a few hours off of work, and drove DS to school. I told the vice principal that I needed to speak to him and was willing to wait. After about 20 minutes, he called me in. It turned out that the teacher had forwarded my email to him, had written the child up for suspension, etc. They took this very seriously, and told DS what he should do if this was still a problem when the boy came back to school. He told us that if anything happened at home, we should call the police.
Bottom line to all this? Normal problems, I email and schedule appointments. Urgent issue, I expect it to be handled immediately.
And yes, my expectations have always been met.