PTC heaters are cheap and relatively simple, but they are also the less efficient way to heat your interior. That is why it is always advisable to choose a heat pump when you have this choice. In addition, PTC heaters are often used to heat the cooling circuits of batteries. So that in winter you can bring the battery to its temperature with the cooling water. Here they are used because they don't need a lot of room and are very compact.
This enables a significantly better charging curve and also a longer range than if you let the battery heat up from its own waste heat.