This is so obviously true for non-tech elderly folk that don't already have smartphones. I can hardly believe it's in question.
Card:
1. Receive free card from bank in mail.
2. Keep card in your wallet/purse which you already take every time you go out.
3. Memorise PIN (the tricky bit, to be fair).
4. Wave or insert card for payment.
Phone app:
1. Either find a phone shop and ask for help, or figure out how to securely buy a smartphone online.
2. Figure out how to set your phone up. This involves a lot of confusing decisions such as whether to create an apple/google account, which services to enable, etc... .
3. Learn how to search for, install, and use phone apps. The parking app will vary depending on where you choose to park.
4. Set up google/apple pay or your card payment details on required apps.
5. Learn how to connect your phone to wifi if you end up parking in an area with internet but no phone signal.
6. Remember to take your smartphone with you every time you plan to drive and park somewhere.
7. Muddle your way through what is often a bloated, ad-ridden app every time you want to park.
It takes fewer “clicks” so to speak and is more accessible to the elderly.
But anything government which doesn’t require to keep track of a purchaser’s identity should accept cash. Otherwise what’s the point of cash if your own state doesn’t accept it.