Technically, they're not color blind - they just can't distinguish as many shades. Kind of like how some people will just say something is blue, whereas another person will identify it as cobalt vs. royal blue or whatever. http://www.pethealthnetwork.com/dog-health/dog-diseases-conditions-a-z/are-dogs-really-color-blind
As for delivery - we've never had something stolen, and we get packages several times a week (damn you, Amazon Prime!). Multiple times, we've had stuff delivered to the wrong house - specifically, the other house in our neighborhood with the same house number, but a completely different street name. *sigh* The package delivery alerts are handy - if I'm told something's been delivered, but I don't see it, I walk over to the other house and just take my boxes. So far I haven't met the people.
Sometimes the sender will require signature, like for a laptop, and then of course we're usually not home and need to go hunt them down at the processing center.
We have loud dogs who lose their sh*t whenever the delivery guy drops a package on our porch, but I don't think that would deter a thief - unless perhaps they just don't want to risk the noise causing someone to look a little more closely.