Grapevine, Texas
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Maybe as a "Drive throug", rather than "This lane is open" indication.
I see a lot of those at Maryland's bridges and tunnels.
A used car salesman probably sold them.
"Yeah, that's completely normal. I sell all my arrows that way. My parents, kids and brothers all have up-pointing arrows and they love them".
I personally think up arrows are slightly more intuitive since the appear to be pointing forward. But either way, whether they're pointing up or down, the meaning is still obviously the same. In fact, I wouldn't care if road signs switched to up-arrows, assuming they did it consistently.
This is the kind of thing only a roadgeek would notice and care about :-D