No, Mexico. California doesn't border New Mexico, but they do border Mexico.

That's Old Mexico

Ah yes, for all of those thieves looking for a quick buck driving 1300 miles round-trip to Gallup instead of a quick hop down to TJ where they can grab contraband for the return trip. I guess instead of drugs, the New Mexico bandits can bring back some of those cheap (cheep) small-cage eggs back to California, but they’ll have to be fast, like Burt Reynolds did with his eighteen-wheeler.

The boys are thirsty in Atlanta and there's beer in Texarkana and we'll bring it back no matter what it takes...

There’s so much to unpack here.

What do these "unpacking" comments mean, and why are they getting progressively more common on HN? I don't feel they add much value.

Here "to unpack" is used in the school literature class sense of "to analyze in detail and discuss". Thus, "a lot to unpack" is a flippant suggestion that a comment could serve as a fruitful subject for discussion (meaning: for unfunny jokes, speculations about the commenter's mental state, socially disapproved activities, and/or political affiliation, etc.)

An "a lot to unpack" comment adds little value by itself. It's basically a verbal reaction emoji.

Burt Reynolds drove the Trans Am. Jerry Reed drove the eighteen wheeler.

https://en.wikipedia.org/wiki/Smokey_and_the_Bandit