I would agree if the OP were a DM already, but they are a DM trainee. They are PAYING to learn to lead certified divers and to help with classes. They will get more TRAINING by sitting in on or participating in the debrief than by hauling gear around.
When the other students have gone, the DM trainee can certainly help with the gear, but it shouldn't be at the expense of their own training -- which isn't on how to haul gear in any outline I have ever seen.
I may have been confused by the word "trainee." If someone is learning to be a divemaster, then the normal term is "divemaster candidate," commonly abbreviated DMC. Once a person is certified, that person may need to receive more specific training on the ins and outs of a dive operation. I would call that person a trainee. There are operations that specialize in this.
If a certified DM is being trained, then that training should be specific to what was not in the DM certification process. This past winter a dive shop I used in Florida had several DM trainees. Here is what I saw happen.
1. They helped hump all the gear to the boat, just as a regular DM does.
2. They helped the customers get to their places and make sure they were all set.
3. They gave dive briefings under the watchful eye of a regular DM.
4. They submerged with a regular DM to set the ascent/descent line on the wrecks.
5. They helped divers get in and out of the water.
6. They helped hump the gear off the boat, just like a regular DM.
7. They accepted tips, just like a regular DM.
Note that they acted as DMs, with an experienced DM working with them the entire time. That is what DM training should be.
If a newly certified DM is just assisting a class with no understanding that they are being trained for specific tasks--as described above--then they are not trainees. They are just inexperienced DMs. They should be paid as DMs. If they not yet certified, it is a different thing altogether.