Just to add my two cents:
Headlights alignments are just like wheel alignments. They "should" be done every two years as maintenance. Things like removing to change bulbs, rocks hitting, birds hitting or people falling against them will leave them out of whack. Does everyone do a wheel alignment after two seasons of hitting pot holes? Probably not, and headlights are even more ignored.
I too have worked in this trade for awhile, and "most" vehicles have at least some way of adjusting the headlights. I also am very sick of being blinded by mis-aligned headlights or illegal HIDs in regular housings (yes, read for off-road use only on the box! Not only that, but the housings are only DOT approved when the specified bulb is used, not a high power/high voltage substitute) The only housings that should have HIDs in them are the factory projectors, because they have the proper type of reflectors to avoid blinding other people on the road (see BMW, new style F150/explorer or many others)
On the another note: most shops I have worked in, including a Ford Dealership, have some sort of headlight alignment setup/machine/tool. There are countless types/styles out there. The 25 ft marked wall is also an acceptable setup.
Sorry for the long winded rand about HIDs, but I HAAAAAATE how many people put them in and have no consideration about anyone else on the road. And those who have headlights mis-aligned are no better.