Blasphemy!!!Having finished a few 80% AR lowers, they do not make sense financially. When Anderson stripped lowers are available for under $40 each, and a background check is under $20, the cost of the 80%, jig, end mill, and router, not to mention your time machining and cleaning make it clear to me that there is another reason for the 80% market.
For me, it was the desire to have unmarked lowers. I could easily put the serial number, manufacture information in a less visible location. If it was just the serial number, that would be pretty easy to make unobtrusive. The roll marks, safe, semi, markings offend the aesthetics for me. Who looks at the safe, semi markings on their AR? My Colt lowers don't shoot better or worse than an Anderson. Finding someone who can do Type III hard anodizing on a non-serialized lower is practically impossible, and home anodizing is not the same as Type III from a good metal fabricator. Cerakote or alumahyde are about the best home option available as far as I know.
What others may want with their 80% builds, I won't speculate. I find it highly unlikely that it is your average criminal looking for a crime gun, as guns are much easier to obtain via burglary or straw purchase. As for staying off of the government's radar, if you are here, you are all ready on the screen.
Be safe.
Having “the man” not know everything you have...priceless