[William Tell]

That drone flying across our border is controlled by radio signals that say, “here I am.”

I see no reason why a drone would have to make a transmission. GPS reception would enable a drone to fly its way to any location within its fuel range to within about 15 feet.

If it fails you might have to find it but chances are smugglers will use a large flock of drones and make multiple flights. Any single loss will be of little consequence.

I just bought a small drone for my son-in-law for Christmas. I wonder if it could carry enough payload to make it autonomous?

[NorthMountain]

I see no reason why a drone would have to make a transmission.

It doesn't. Less than $1000 will get you a quadcopter that will fly for about 20 minutes, completely autonomously.