Most U.S. federal judges are aware of the differences between drawn and real. They understand the 'no one is being hurt' argument as it applies.
It came up in a court case about photoshopped cp a while back. The judge involved said he couldn't, in good conscience, rule that it was really cp since no one was exploited to make the image.
Accordingly, drawn lolicon art is even more immune than photoshopped since it's impossible to even confuse it for the real thing.
The problem here is not the laws, but the cops who want to enforce them.
Regardless of which country they live in, Japan or the U.S., cops get wet and hard for possession crimes. Drugs, illegal tech (like mod chips), or cp. It doesn't really matter to them. If you think they're out to 'protect the children', think again. If only.
Possession crimes, CP in particular, are easy to investigate and easy to prosecute. You don't have to show motive. Most of the time the cops don't even have to take it to trial. They say 'child molestor' in a loud enough voice that the world ends around the person they busted... regardless of if they actually did the crime.
Most lawyers will try to tell you not to even bother defending yourself. Take the plea bargain because if the case actually goes to trial, all the prosecutor has to do to win the is show a few pics to the jury to make them angry enough to put you away.
The busted lose their job, they lose their families, they frequently lose their homes. They go on a sex offender registry for the rest of their life.