I'm not sure if you realize how moronic you sound. Roundup, when applied correctly, is incredibly commonly used for doing exactly what I outlined - killing the vegetation in a field prior to plowing and planting. I'm going to assume you're a citiot (idiot from a city who thinks he knows what happens on farms) and not someone who lives in any sort of rural area. Glyphosate, when used in prescribed concentrations, is extremely safe. In the environment, provided it doesn't get into ponds, etc., it rapidly breaks down. Spray, and plow under a few days later, after it's had a chance to migrate through the plant to the roots. Thus, with annual crops, even without round-up ready seeds, weeds can be minimized. How the hell do you think weeds are cleared from new farm land? 10,000 illegal immigrants wandering around, pulling them out by hand?? No. Herbicides are used. Glyphosate being one of the most common, and is often mixed with 2,4-d (another common herbicide).
You've referred to ill health effects of glyphosate - and those effects are from excessively concentrated (if not drinking it straight out of the bottle.) You may as well tell people not to put salt on their steak because if you consume 3 kilograms of salt at once, it can kill you. To spray an acre of field to kill off, say, grass, you would use roughly 1 quart of 41% concentrated glyphosate, with a lot of water. Roughly 1 part in 100. Other types of weeds require up to 2 or 3 ounces of concentrated glyphosate per 128 ounces of water. I don't recommend it, but you could probably drink an 8oz glass at that level of concentration, without any major ill effects. I routinely spot kill certain types of weeds in my pastures - types that spread quickly and that are nutritionally poor for my animals. I can't stand thistle. I've never had animals get sick from grazing on weeds that have been sprayed.
Again, at the most, 3 ounces of 41% glyphosate per 128 ounces of water - and that's enough to spray hundreds of square feet.