Dirk the Daring (this time with the “the”!) says,
She may see things, but I don’t.
I’m truly baffled too. Unless Rosa is nine feet tall and is looking over the tops of the shelves, which I’m pretty sure she isn’t.
P.S. Unless WordPress is flaky (always a distinct possibility), this is the first time Rosebuds has made CIDU!
Comics I Don't Understand 
Based on the next day’s strip, Rosa does tower over the cashier. She may not be nine feet tall, but I’d say she’s at least seven.
Health and Beauty departments do sometimes have shelving units that don’t go as high as the ones in grocery aisles, so it’s not unusual that she can see over these if she’s seven feet tall. But I think she’s also having her vision blocked by the aisle signs, which normally would be too high to block anyone’s view.
As a POH (person of height), I can attest to seeing things that most people do not, like dust on top shelves and other high places (and the tops of people’s heads floating down adjacent aisles).
If you want to make my day, be a diminutive, grandmotherly type in Walmart and request my assistance at getting something from a high shelf.
Funny timing–my phone decided it didn’t like the network it was on, so I opened this post and there was no comic. Which meshed perfectly with the title! I was prescient when I wrote the post. (Reconnecting to the network fixed it)
It does appear that in the third panel, the shelves only come up to her neck height, so I assume Max is right. I wouldn’t know, as I’m only 5′ 2″, and have asked “to borrow the height” of tall people like Max to help me reach something on the top shelf.
FYI, folks, WordPress seems to be in a mood: there have been three comments marked as needing approval so far today, including mine above. So if you post and don’t see it, give us a chance to approve it! Hopefully they’ll fix this soon–I’m sure there are much higher-traffic fora where it’s going to be far more irritating, so I’m not investing the time to figure out how to complain.
It might have been more interesting if there was something on top of the shelves to be seen…candy wrappers or brochures or something. That might have made it a bit clearer.