What should be viewed as more unique actually is how verbose North America is. Especially in the car part that I know of, watching car reviews online - road signs or even buttons in a vehicle that would be symbols in Europe or Asia are written out.
It’s weird because no one has a phone that looks that way now. Does the younger generation even know that it’s a phone? Same with a lot of software iconography.
Even then, most call icons I've seen don't only have the receiver as part of the icon, but some waves to, to indicate sound (speaker/sound icons often do the same, unless intend to mean 'mute', but that's usually paired with a cross or something). Given that, you could probably get away with anything half-moon-ish shaped, so long as it also has those waves on the upper end of the icon, and it'd still be recognisable as a phone receiver and a 'call' icon (please don't do that though. Just make a normal icon).
Having an icon of smartphone in a smartphone for the call app wouldn't be very helpful. And considering modern usage a smartphone doesn't even a have a strong association with calling.
The symbols on a European car (TBH I've never noticed the difference in a hired American car) don't have this problem. They refer to real things, like lights and fans.