This is probably NOT some the "I only play E-flat, because it does everything" type of player, but it may possibly (??) be for the "I'm running errands before-and-after this rehearsal/gig to save time/gas" type of person...
...and it's certainly for someone like ME - as I find myself with multiple personal instruments in my car (often: one of various tubas verticalized in the front passenger seat - possibly also with someone's repaired French horn...or some fairly heavy purchased-on-the-way items...on the seat itself).
I almost never carry any human cargo...ie. ALMOST NEVER does someone ask, "Hey bloke, can I ride with you from where you live in the middle of nowhere to your gig, as well as to some supply house, and to someone's house to drop off their repaired instrument?"...and it would be nice to (simply) keep one of these stuck in that slot (until-and-if there actually is a passenger), because it just doesn't occur to my to reach over there, pull out the seat belt, and click it in the slot. Also, the seat belt (when I do that - to stop the intermittent beeping) tends to get in the way of the things I'm carrying in-front-of/on that seat.
With my car, going over a bump or bottom of a hill can suddenly make the heavy stuff (in the front passenger seat) suddenly push down hard enough to "feel like" (to the sensor) that it's heavy enough to be a person, and the beeping commences - over-and-over, as the same conditions occur over-and-over.
because the BACK is often ALREADY full - thus wedging the last of the stuff in the front passenger seat and the slanted vertical space in front of it. This isn't just "extra tubas on the way to gigs"; it's also picking up a surprising large load ("Hey bloke, we found some more stuff for you") of repairs from a school, and being in my car - rather than in the work van (and/or "getting by" with the car - rather than the work van), due to the heavily manipulated fuel pricing....but bloke, why don't you just put those things in the BACK...??
...so it's probably not for everyone but - if there's one (not necessarily this brand) on eBay for four bucks - it could be for me.