500kg load and 4 pax + pilot? uhm, not in the US, my friends...
The real problem would be how the FAA would class such an aircraft. Whether multi-engine or single, and whether each proprotor is separately powered or there's a central powerplant and shafts running to each proprotor. If the FAA/Euro equivalent calls it a Single Engine aircraft, then the bird is relatively easy to get pilot training for. If you need multi-engine ratings, that's a lot more training required.
And using it like a taxi, you'd need a commercial pilots license because you're flying for hire.
Hypothetical VTOL Aircraft,From Real One
TsAGI Stalker-501 « Ulun » tilt-rotor transport project
NICETRIP - Novel Innovative Competitive Effective Tilt Rotor Integrated Project