Let's begin the supervised product that was the seed for creating this blog: Murphy Oil Soap Wood Floor Cleaner. It's not food and not used with food vessels.
I tried looking up any reasoning on the OU site, but finding none, tried tweeting @OUKosher What does it mean when you certify a non-food product? Why does my floor cleaner have a hekhsher? #kashrut
though I have received no response.
For consideration, I am posting two articles for thought:
1) An articule on the OU site about the kashrut of soaps. The article begins with this quote:
Food companies recognizing the profitability of the kosher market have pursued kosher certification in an effort to increase marketability and sales of their products. What has been especially remarkable is that the pursuit of kosher certification has not stopped with food. It is not unusual to find nowadays a hechsher on non-food items. Are there really any viable kashrus concerns with something that is inedible? This article will focus on dishwashing soap.
but never actually addresses the broader question and doesn't answer why the OU chooses to supervise soaps (and our above wood cleaner).
2) I did find a blog post about the Hardei (ultra-Orthodox) Bada"tz in Israel admitting to supervising things that don't need it.
which provides this translated section:
"It comes from the public" says, Harav Avraham Joseph who is in charge of "Products that are inedible" in the בד"ץ Badatz. "The factories hear the demand" of the public and ask us to give a Hechsher. Bleach of example, is a product which is inedible and poisonus, and to begin with has no fear of being Hametz. It really "Doesn't need a Hechsher", explaind Joseph, "That is also how we answer people who ask us directly."...As I am sure you can guess, this blog has no hekhsher of any rabbinical authority. If you ask if it's okay to read it*, you'd likely receive a response of "it's not recommended". Which means "it's probably okay, but, you know, politics".
The Rav from the Badatz sees nothing wrong with unnecessary and expensive supervision of the Badatz "Ultimately the Badatz has a purpose - to serve the public. If there is a public demand, we are here to give the public the service that it needs and is interested in."
* And why are you asking a Rabbi if you can read a blog post? Just use the kosher internet he certifies. If you have any questions, you can call on your kosher cell phone.