I believe Wa8yxm was talking about the tow vehicle's license plate NOT the trailer's plate.
Personally, it's a neat little trailer for the person with money to spend and no real need of a trailer but who enjoys quirky stuff.
Realistically, being able to fold the trailer up while hitched isn't really practical. It doesn't reduce the space needed to store it when not in use (eg, garage or driveway space). And when it's hitched, as mentioned,it blocks the ability to access the back of the vehicle, so you aren't going to want to drive around with it hitched and folded all the time.
In limited use as "extra storage" on the road for a motorhome, it could make sense. But for other "casual use" to haul stuff, I don't see it being that great. It'd be easier to use a bike rack, rooftop carrier, etc.
And for professional use such as landscaping, it makes no sense at all - most landscapers store equipment permanently in their trailers, so they'd never empty it completely and fold it while hitched. It makes no sense - especially sense they couldn't open their truck's tailgate while it's hitched.
Even for something like moving, the benefit of "folding it up and parking" is minimal. You still have to find a place to park it extended to remove everything before you could fold it up. And once you've removed everything, you're done and can just leave, so why waste time folding it to find another parking space. And let's be serious, most college students don't want their parents hanging around the dorm all day - "get my stuff unloaded and in my room, then go away before you embarass me".