Because carpers are generally looking for abrasion resistence and knot strength, as opposed to diameter, then you are buying 15 or 17lb line, packaged as 10 or 12.
Look thru the archives on here and you will see loads of comments about peoples preferences, the limited number of manufacturers in the world and the scams etc.
I have been using fox soft steel 12lb so far this year and have had no problems with it. Its quite dear for mono and but i have had no problems with it. ?14.99 for 1020m so good value.
Crazycarper1