Arrogant and ignorant at the same time; kudos to you.
No, kit lenses aren't L glass, but one of the reasons for their price is the fact that lots of them are made, reducing the unit cost. You remember Econ 101, right? If you can't produce a good photo with Rebel/kit glass, your creds as a "professional" are in doubt.
The reason they're cheaper is less expensive structural design (e.g., single zoom and focusing helicoils instead of double helicoils), les expensive materials (e.g., more plastic instead of metal or aluminum instead of brass), and simpler optical design (e.g., variable maximum aperture or smaller maximum aperture).
That might reduce versatility, maintainability, and robustness (all factors valuable to a professional), but as I've said before, at the middle f-stops where family portrait photographers live they're just as good. In a family portrait taken on a nice afternoon at f/8, there is no L lens that is an optically superior choice to the Canon 50mm f/1.8.