When I was small there was an actual "canning business" for the homemakers in town. I recall every year for 2-4 afternoons, (depending on the specific items being canned)  Grandmother and mother would take all the fruits/veggies/ etc.. they wanted to can to the cannery. There were huge long cleaning packing tables there, got a spot at one of the tables, peeled,cleaned, and packed the tins with veggie of choice,, and once you had all your cans full, a worker would take your "racks" of cans to the canner. The cans were "steam blanched" lids were put on, the can's were sealed, and about 20-30 minutes later your "canned food" was cool enough and rolled back out of the canner.  Then G.M and M. would mark what was inside the tins with a marker.  Racks were rolled out to car loaded and went home.

We had canned food all year around, the actual expense was very very minimal, and there was a lot of pride involved in having your "own canned food"..   Granted it was not convenient  but always knew exactly what was in the can.  Wow,, a whole 3-4 afternoons out of a year.  Was it "safe" ???   Well Grandma  lived to 90 plus, and was never sick, same with mother, and I never got sick. 

Pffffffft...  cans were always steamed enough to kill all 'bugs' and immediately lids were put on and sealed.  Probably alot safer than today's canning process.  Cannery's today don't eat all their own work,,,, we did...

Hated to see the cannery shut down,, it just wasn't convenient for people.   LOL.. it's so much more "convenient" to pay $1.30 for a can of chilli in the store with zero knowledge of how the chilli was produced...............