Its becoming more of a problem as aftermarket LEDs get more popular. The xenon kits were only installed by people who wanted to be 'cool', but LEDs are getting installed by people who want to save money or effort in replacing their halogen headlamp bulbs.

What is worse about the LEDs is that they are sold as "compatible" to various vehicles, when that means they will work mechanically/electrically, but not optically (some actually try to put LEDs in the same spot as the filament). All of the units I've seen cause the car headlamp to put out light at higher angles than a halogen bulb will, causing more glare for opposing traffic.