[wdfifteen]

I'd put my money on alignment. If the steering rack (or steering gear depending on which it has), isn't centered, the alignment at the wheels can be fine but not return to center. Centering the box/rack is part of a proper alignment.
I wouldn't trust a place that would check the alignment and not check the operation of the car to see if there are any issues.
My SO took her car in to have a thumping noise in the left front corrected. The shop repacked the wheel bearings and gave the car back to her. They never test drove it or they would have noticed that the noise was still there. Turned out to be a belt separating in the tire - a real safety hazard. The manager of the shop gave her a new tire. He didn't want to be responsible for an accident cause by a faulty diagnosis, especially when a "repair" had been made and paid for.