I can find no advantage to ordering seeds using a PO Box. The post office requires multiple forms of ID including a picture ID. Anything that goes to a po box is easily tracked to the owner of the box. The UPS Store and similar outfits don't offer anonymous options either. Using fraudulent identification is something I'm not inclined to do and wouldn't even know how to go about it if I was. And anyway, I see fake or stolen ID's as as a security risk in and of itself unless you are a pro at such things.
Am I missing something?
Unless you use a third party go-between (which brings with it a whole new set of security risks to evaluate) I'm not aware of any delivered by mail method that offers any real measure of security.
Luckily, when US Customs does intercept a package they simply confiscate the illegal material and send you the rest of the package sealed with their green tape plus a letter like this.
My opinion is that only an order of many hundreds of seeds or something clearly big-time will cause US Customs to step outside of their own massive bureaucracy to contact local authorities. And even then, such authorities still need to go to a judge to get a search warrant before they can get any information on your adequately hidden grow.
I've heard of only a single case where an intercepted package resulted in the police knocking on someones door. And those people actually let the police inside their grow area and voluntarily admitted their activities (so said the news report). I'm confident that very isolated case had a lot more going on with it than JUST a confiscated seed order.
If confiscated seeds were leading to arrests of typical people I think we'd hear about it every now and then. But we don't.
I'm 100% in favor of all well-reasoned security measures. But order seeds without involving outside help just doesn't allow for many options.
$0.02