I'm not entirely sure I understand.

My understanding of "brake check" is a road rage incident when one motorist will apply the brakes quickly because it is felt that the following motorist is following to closely. In an effort to, "teach him/her a lesson" about following too close.

If this is correct, then my perception of the original post, seems to describe that some (or many) motorists are approaching an intersection too fast and applying the brakes late.

What I'm not sure of is how this affects you. I doubt that you're travelling at 30mph on bicycle, behind these people, and affected by these quick stops. So, it must be some issue when they pass you at an intersection and stop quickly(?)

I'm also not sure how shining a light into their eyes would communicate to them this issue though.