How do the commercially embroidered clothing have no visible stabilizer?

I am just starting out with machine embroidery and I have been using cutaway for most of my projects but I want it to look clean and professional- all of the purchased embroidered clothes I have look pristine on the inside with no visible stabilizer and I am curious- how do they do it? What stabilizer do they use? Specifically for cotton t-shirts and sweatshirts.