Back a bit farther than 2015 if you didn't want anything slabbed as "A" they would send back a slip with the notes.
The reasons above are the most common, but a lot of other stuff would get slabbed as "A".
The unfortunate thing is that most collectors only look at size or straightness, but not the details of the cut. So anything factory but unusual gets tossed into the "A" category. See below.
Using my slightly less than scientific method for checking straightness from scans(a bit of cardstock held up to the flat monitor as a straightedge)
The top is actually straight.
The left side does appear curved, but... the pics are phone pics not scans and were taken at an angle so there may be some lens stuff going on.
The image of the card is narrower at the top than bottom, and the right edge has a similar curve, so it presents sort of hourglass shape. That makes me lean towards a lens/range etc issue more than an actual curve.
Curved cuts can happen, but would not be concave on both sides.
Here's one I sent in that is nice, but was rejected for very rough cuts top and bottom. That is often from a dull blade in the cutter.
This one would be rejected, but is facory cut. This odd cut comes from a bit of debris either in or below the stack of sheets being cut.
The other two I had rejected, one was factory but undersize, the other actually trimmed all around, (an embarassing miss on my part, rushing to get 10 I thought were good enough to bother with near a submission deadlne. )
All 4 would be slabbed "A" but only one really would deserve it.