We see this as well. I suspect its probably down to the automatic headlamp adjusters as mentioned and also that there is probably discrepency between one headlight tester and another.

Also lots of bulbs not fitted correctly...wonder if the position of the bulb and or filament by 1 or 2mm adds up to much more on the headlamp aligner?

We charge full price so as long as its a 2 minute job, no charge is made.

Cheers

Sean