Just reading some of the other quilters' contributions, I have noticed too that my LQS's do tear the wide fabric for backing. I have never asked for it to be cut, thinking there's probably a reason why they tear it, and I've never had a problem with my wide backing as a result.

Tearing fabric is not commonly done now days since the fabric making/weaving process has become much more refined and quality fabrics usually have a pretty straight grain.
You only tear 100% cotton, some silks and some velvets as it will give you the true grain of the fabric. That makes it easier to square up your yardage for anything you are making. A distorted grain can ruin all your hard work in making the perfect item be it a quilt, bag, dress or potholder. If you are buying fabric of questionable quality, ask the clerk to rip it--if it doesn't tear, it isn't 100% cotton that means you may not be able to straighten the grain if it's crooked. If you really love it (the fabric), you may need to change your plans for it.

I have seen fabric both cut and torn. Tearing is suppose to give it a true straight cut. The local quilt shops around here are very precise when they cut using a ruler with lip to get a straight cut. One store even had a slit in their cutting table to use a guide. I prefer a cut edge because when I wash and its already ragged it tends to get more so

I have found that when they tear the fabric, you lose a couple of inches from the horizontal threads "pulling" as they rip. I always ask them to cut and have never had a sales rep refuse. Sometimes you lose a couple of inches as the fabric isn't cut "on grain", so either way I always buy extra. :)

Usually when the cut the don't you need a table with the straight cutting whatever on it - if the rip the fabric - maybe they are not set up to cut it.

Some LQS rip instead of cut. I was told that it will be sure to
be on the straight of the grain. I don't like the rips either but that
is the reasoning for ripping.

When I took home economics in high school we were taught that tearing gives a true grain to the fabric edge. Don't know if that's actually true or not. But, I have always done it that way. I just trim off the raveled edges.I only do this on cotton or cotton blends.
Frankie

I like mt torn becuse it tear with grain

Most fabrics tend to twist when being rolled onto the bolts at the manufacturer, and can be off by as much as 4-6 inches at the beginning of a brand new bolt. Many untrained staff at some of the fabric stores don't know of this, and just cut without evening up the fabric first. Ripping of wovens is actually more accurate. I was trained to only cut true woven plaids such as ginghams, and then a single layer at a time. Does it matter? If you are putting on a pair of pants (chinos) that have not been cut on a true straight grain, they will pull in the seat with every step you take. On a quilt of small pieces it may not be as important.

I have had the same problem (Joann's) & would lose inches because of uneven measurements. I did email the company and also returned the fabric to Joann's & asked for the right yardage. It is frustrating & inconvenient to say the least. I know the employees are instructed to cut the exact amount and not give an extra inch. What could be a solution to this problem ?
I have never had my fabric ripped, always cut with a rotary cutter.