I think a lot of "serious" collectors dismiss them because they are not particularly rare or expensive; which is a shame because they are very historically interesting. I have the same problem with milk tokens. It's difficult to find information or catalogues or other people who are interested in them.
I've got a handful. 16 to be exact. I like them, but I have so many other areas of interest that they always seem to take a backseat. Though I have the same number of them, I find parking tokens to be more interesting. Many of them seem to use negative space and cut-outs and it's just beautiful.
"What we are is not as important as what we aren't"