I wear work pants all the time, most of them have sewed on patches - learn how to use a sewing machine here. The pair I had on yesterday had recently developed a new hole, and a tree limb snagged in that hole yesterday. Unfortunately, the tear was quite large, and the dungaree cloth was weak already from previous repairs.
I love using the my sewing machine, I think its the original 3D printer. Its an intricate machine with lots of moving parts hidden behind a plastic case. I don't know what many of the knobs and adjustments do. But I am able to sew patches on pants with it.
So it was time to retire this pair of Carharrts, though they have served me well. But the silver lining for pants that can't be repaired, is that you can salvage the cloth. This cloth can be uses to repair other stuff. Typically the back of the pants legs are still in good shape, so sharp scissors make quick work to remove a large section of cloth.
The rest of the pants can be recycled in one of those drop off bins you see in store parking lots. From what I understand, any clothing not intact is sent to be used as insulation or filling. Please don't just throw them in the trash.