When I first started sewing (in the 70's) it was common practice of any establishment that sold fabric to cut a bit extra to make up for the fabric being on the bolt crooked. I can't remember what the common amount was. Maybe an inch to three inches per cut?? As the years went by the fudge factor that fabric stores gave went by the wayside. I remember not sewing for a good 10 to 15 years and was surprised the next time I went to a fabric store and they cut exactly what I asked for with no extra at all. After I got home and washed and refolded I found I would lose up to an inch of fabric when I squared it up. On average it was usually less, but sometimes much more .
I rarely buy fabric from a pattern, so I am usually getting a couple yards of this or that. But if I do buy from a pattern I always get more than I need. Most of the time I am only cutting off a few threads to a fraction of an inch when I square up but I have had a few purchases that were so cattywhompas I lost a couple of inches on a one yard cut.
I don't sweat it. To me it isn't worth the effort or frustration to try and argue with the LQS over a few fractions of an inch of fabric, especially when most of my fabric purchases are done on line. More often than not it is only a few threads. I am now pleasantly surprised if I get extra. I expect to get at least what I want cut but if I lose some in the squaring up I don't get upset (any more)