You need to be more selective about alignment shops...actually, you need an alignment shop, not a tire store, if that's where you've been trying.
I deal with this a lot in my collision work...most tire shops (ESPECIALLY the chains) are of a "set the toe, collect the dough, let it go" mentality. You would be surprised how many "alignment techs" cannot even tell you what the symptoms of incorrect alignment angles are. All they know is the machine tells them it's in or out of spec. Most do not understand that a printout can show each side to be "in spec", yet the car is not really aligned properly.
The biggest problem is that most places sell alignments at a fixed price...far below all the labor guides time for an alignment. The faster (less effort) they can get it out, the better. The stories I could tell...local Firestone store doesn't even road test them after. We stopped using them after the third time we had to go right back in because the steering wheel was not even close to centered. Just sloppy sloppy sloppy workmanship. The last shop I was at finally bought their own equipment because the local guys just would not get it right.
ABSOLUTELY tell them when you drop it off, that you'll need a spec sheet showing before and after, if they advertise a computerized alignment. Best bet is to find an old school alignment/frame shop...most of them know what the H they're doing.
There ARE tire stores that know what they're doing, but they're few and far between.
Places to avoid, based on my market...Pep boys, Hibdon tire centers, Firestone stores. Hit -or-miss chance...Big O tires, Goodyear stores. Big O and Goodyear are usually pretty good here, but it's hard to keep a good alignment tech around if they're not booked solid most of the time.