It's very much cheaper for us to buy commercially produced jars of fruits, soups and so on.
The 700ml jar of cherries I bought last week cost me 89p. The fresh cherries are nearly £6 a kg. I can pick my own, but the jars cost over a couple of pounds each too, and though those are reuseable the seals aren't and cost 40p a time (because I do a lot of this I know when to look for the sales, so I don't normally pay that for mine, but that is the usual price) add in sugar (cheap just now at 70p kg) and the heating and it all adds up.
Jam making's not so expensive and a lot of people do that, and a fair number make wines too. Freezing is commonplace, and since power cuts are very, very, rare, generally secure. Pickling is pretty straightforward, and again fairly common.
American quarts are smaller than UK ones, but pretty close to a Litre in size. 3 kilner 1lt jars cost £8.99.
M