That's the idea behind the suitcase kit. All but the snare and hihat stand fit inside. But, of course, the bass drum sound is highly compromised. The suitcase kit is also one trip, but three cases, including a huge hard shell golf club case.... Now if I could buy a set that came with a nice 1 piece case for all the drums that came on wheels, that even included a spot for hardware?
I'd be into it.
It's actually easier.
It's not the size of the drums, it's the number of trips back to the car.
The real problem is the weight of all the stands and hardware in just one case. There's really no way to lighten a drum set much when you want a four piece kit plus cymbals. There will always be a compromise somewhere.