You are missing one important aspect of current day xenon headlamps.
Xenon bulbs are placed behind a horizontal shield that blocks the top half of the light and only allows the bottom half out. That is followed my a projector lens that concentrates the light forward.
If you place your hand directly infront of a xenon headlamp you can see the line. If you place an object directly in front of this line you will see a shadow.
The light in a xenon projector headlamp is directional kind of like a laser.
It is different compared to your standard halogen reflectors that just shoot light in all directions coming out of the bulb.
Lights that output from current day xenon headlamps look like this
It is much like a laser where the light is aimed at a direction and not anywhere else.
This is what headlights use to output
No direction. Just anywhere the reflectors aim it.
How do I know this for sure?
Well when I head to track events I like to tape up my headlights in a cross to indicate the car is an off road car. I can see the projector cutoff having dark spots around where tape lays. It's not a clear shadow but the light output is decreased simply because projector housings are so directional (kind of like a laser)