I remember receiving my weekly pay as cash in an envelop back in the late 1980s.
By the time I travelled to Europe for a working holiday in the Early 1990s I was able to take a credit card and use it to pay for things, thought I couldn't make repayments from Europe. In fact I mailed a bank cheque home to a friend to pay my credit card bill, which was promptly rejected by the bank as it was a UK bank cheque.
At the time I couldn't use an Aussie ATM card overseas or access my Australian financial accounts online (it was pre Web).
By the 2000s when I was travelling regularly internationally I was carrying about 50% cash and using ATM and credit cards around half the time - depending on where in the world I was going. Some countries were still mostly cash, but I had access to ATM withdrawals almost everywhere (at least in major cities). At this time I stopped carrying emergency travelers cheques as they were no longer needed,
By 2010 I was travelling with cards only, rarely taking any cash with me, and only when travelling outside major cities. I did get caught in Malaysia in 2014 when I found that taxis still didn't accept credit cards, although everyone else there did.
Now wherever I travel it is now PayWave, even more so overseas than in Australia, where some merchants still have old clunky ATM devices. Personally I now have a PayPal device I carry with me to events where I am selling my Social Media Planner cards (smplanner.com), which simply connects to my phone for transactions. Unfortunately I don't have the latest version which now supports PayWave as well.
I rarely carry much cash in Australia, except for Bill-splitting at restaurants (where paying through multiple cards is inconvenient), and occasionally buy a coffee using Bitcoin in one of the still few coffee shops supporting it.
Money is indeed a technology and our relationship with it has changed enormously in the last 20 years - far more than in the 200 years before that.
I am expecting even more shift in the next ten. Paper money will still be around, but digital currencies will become more common and widely accepted. We will make digital payments easily between people using common mobile devices, not simply through extra devices like Eftpos machines and PayPal handhelds.
The goal for financial institutions is to stay in the middle of these, taking a percentage from every transaction as a moderator and validator. So far PayPal has the inside running on this, with Apple a distant second, with most banks not in the running (besides Commonwealth's now axed Kaching).
I look forward to paying for things without a device, using bioprint to validate transactions. Apple Money is a step in this direction, but the device remains King, something Ai don't see lasting.