I generally come down strongly on the side civil liberties, but they don't become involved in this case. Anaya knew
exactly what his clients where using the compartments for; even asking them not to tell him makes that clear. That's the equivalent of clamping your hands over your ears and singing "lalala". He knew. He kept building them anyway, using them to subsidize his other business. Conscious avoidance does not protect you from the law.
When confronted with the knowledge -- $800k IN CASH -- he then charged more than his normal amount to fix it. Again, don't be bloody daft. That's a decent middle-class net worth, in cash, concealed in a car. Unless someone's a billionaire, there's no reason to have that type of walking money besides illicit drug sales.
Any reasonable person would know what was going on, and in fact, Anaya did. That's why he's in jail.
As for your, well, stupid friend example -- you need to do more than just know. You need to actively aid. Which Anaya did! If you have a friend with a low-paying job and far too much money, I'd advise you to avoid holding "packages" for him, or installing concealed compartments for him, or straw-purchasing weapons for him. Again, don't be deliberately obtuse.
edit: One more point. Anaya's calculated ignorance is like Goodell and the videotape. The only way goodell didn't see that videotape is he didn't want to, and the only way Anaya wasn't confronted with exactly what his customers where doing was he actively avoided it. Also -- as mentioned elsewhere -- the compartments were insulated for odor? Come up with a legit use for that.