Did your car have a factory tow hook option? Because on many cars the "tow hook" option, makes the car come with a bunch of stuff. A strengthened rear bar, often auxillary oil coolers for the gearbox, sometimes different final drive, restriction to only a MT, or a completely different gearbox alltogether. So maybe for some reason the US ioniq didn't have the parts available that made the ioniq be safe to tow with...