Until they do (because everything has a failure rate) and cost thousands for an entire new projector assembly. Compare to the cost of a halogen bulb every couple 10k miles.
The MTBF for OEM LEDs is in the decades timescale. Projector assembly isn't called LED bulb for a reason. It's time to nuke this misconception from orbit. If your 17 year LED headlight has failed, you need the part that represents just the LED bulb, and not the entire headlight assembly. See price difference between part 1 and part 9 below:
“MTBF in decades” is marketing fiction. The diode itself might last forever in a lab, but the driver electronics, thermal paste, seals, and optics sure don’t. Real-world LED headlights die from heat cycling, moisture ingress, and driver board failure long before the diode hits its theoretical limit. Most assemblies don’t even have a serviceable “bulb” to replace. Pretending you can just pop in a $40 LED chip instead of the $900 housing is wishful thinking.
Until they do (because everything has a failure rate) and cost thousands for an entire new projector assembly. Compare to the cost of a halogen bulb every couple 10k miles.