There's probably a federal or local law requiring some sound. Like the Waymos that incessantly beep beep beep when backing up at the recharging station at 1 mph. You're about five years away from hearing beep beep beep everywhere you go due to the proliferation of driverless vehicles.

To be clear, the exterior sounds hybrids and EVs make is different from the "engine" sounds the Ioniq 5 N pipes inside the car.