Red and Blue are opposite colors of each other and when you put the blue dot in the middle of your taillight, from a distance it gives a very distinctive color. Even so, You can still determine that it is a taillight so why the fuss?
Up close, just looks like a small blue dot in the red taillight.
This has been around since the 40s and the law people have hassled people ever since.
Maybe one of our Law Officers can give an answer as to the law that governs this issue.
I have them on the taillights of our ATV that we use as a golf car around the development where we live.