I agree. Changing tires side to side should be the first diagnostic step. I personally do about half of our alignments and we do them for 15 other shops including two new car dealers. I always assess the driveability (how it pulls, drifts, wanders, etc.)before I attempt to align.
I agree the car can be aligned by anyone, but I'm not sure you can definitely find an alignment tech anywhere. The chances are probably better at an alignment specialty shop than at the dealer. I have had shops bring me problem long wheel base vans because their customers can't solve their problems after many alignments. The one that comes to mind was being used by a church to haul disabled people needing a wheel chair. It had a lift built into it with about 500lbs (or more) of machinery mounted over the right rear wheel. It caused the ride height to be a full inch lower in the right rear and higher in the left front. I had the other shop add a leaf to the right rear spring to solve the ride height problem and the alignment could be done by anyone.
My point isn't how to align vans. My point is that people align cars not machines. When I drive a MB with a pulling condition I can tell right away whether alignment can fix the car. I can't be sure it can, but I can be sure if it can't. Because I do numerous MBs every day I know how much change I will have to make to correct a condition. Nine out of ten cars that are brought to me for pulling conditions are tire related. Luckily MBs have the ability to correct for quite some tire problems (unlike BMW who has no such ability). Before I fail to meet the customers expectations I always identify the problem first. If I know that I can't correct for the magnitude of pull I start by having the tires crossed. If it changes the condition I align the car to see if alignment has caused the tire condition or to verify that the car is bent and will need further repair.
Bosch Master, ASE Master, L1
33 years MB technician