We used checks. For high value transactions, cashier's checks. I don't know how this transfers to a bitcoin environment. Oh, there wasn't as much mail order back then. Most shopping was local.
The good days, when going out shopping and being able to get everything you need. Shops were full, now where I am most shops are pretty much gone only the big chains remain. All the local small businesses have sadly gone.
i'm not that old but I remember the old mail order commercials offered COD as a payment option.