Our Passat and A4 both had rear footwell lights. But those are also considered mid sized cars. I don't think I've ever been in a "small" car with rear footwell lights. Must be assumed that we wouldn't have adults in the back seat often, or that the limited foot room would mean someone might kick and break the lights.
I have thought about wiring something up, but it's just not worth it since no one is ever in my back seat! My S40 is a C30 at heart
If you have power seats, it wouldn't be too hard tap those for the power source for lights. You could also buy two new bulb sockets and extend the wiring from the from footwells under the carpet (then they would light up when the doors opened). It would be an easy mod. The only concern I can see that you'll need to have LED bulbs because they require less power to be on. Normal foot well bulbs may be dimmed by their power supply being split to two bulbs.