Contact customer service and tell them you didn’t get it. You’ll get some credit and if this keeps happening they’ll either do something or you’ll get lots of free stuff.
Now they’re usually fulfilled by UPS, and I don’t recall any issues since having the flag added.
IIRC, Amazon.com customer support can only request the flag, but it can be denied. That's what happened to me, and I still get stuff delivered by Amazon Logistics.
At least their service has improved somewhat since then.