Maybe it shouldn't, but this subject always amazes me.
Since our great grandmothers time Singer, Greist, and every other company has offered a simple, effective, and inexpensive fabric guide for sewing machines. Yet most people reject them. They are still offered new by several makers and are still fairly inexpensive, but no, they are rejected. A formed piece of metal and a screw that affixes it to the bed, and holds it in place, couldn't be simpler.
Instead uber expensive, over engineered things like the huge plastic ones are suggested, or even worse, things like tape that can and do damage the finish some folks are sooo paranoid about scratching.
1/4" feet work too on some machines, but not on others. You gotta be very careful to measure the seam you actually get with those feet. On some machines the manufacturing variations of the presser foot shaft will cause you to get larger or smaller seams. On the machines I actually get a 1/4" seam, I use the foot. On all others I use the guide.
The old simple bed mounted guides are adjustable. You can adjust them to what ever seam width you want. Regular or scant seams, big wide seams, and some of them even allow you to make seams around a curve. Some have notches in the guide side so you can use them with straight stitch feet mounted on ZZ machines, or parish the thought, on left homing machines where you really can make 1/4" seams with them. Some have guides on both ends, wide and narrow, some are stamped steel, some are cast iron. A version for every need.
And if you're paranoid about scratching the bed, put a piece of felt or fabric under the right end. The left end almost always sits on the needle pate so it doesn't touch the bed at all.
Fantastic tools, if you're like me and can't keep your fabric straight without a guide, you should try them sometime.
OK, I'm off my soap box now.
Joe