Good eye Sir. I have trained my crew to do it the right way. Plus, the foundation inspector also does a good of hammering them on it also.
The biggest lie told in concrete construction is that they will lift the rebar, or wire, while they spread it. I've seen pictures of them doing this at first, and then the mud starts to flow and nobody has any time to pretend anymore. The rebar, or wire, gets walked on and pushed to the bottom of the mud, where it's worthless.
Chairs are cheap, easy to install and critical to a quality job.
I'm looking forward to more pictures of your work.