That said, there's a pretty clear bifurcation between a lot of retail banks that are happy to make money off all the small accounts and lazy money in checking accounts and the brokerage money market and other accounts paying around 4% or so these days which are actively pursuing deposits.
Not to mention peoples money would smell like their beds. I prefer using safes for quick access things and deep unmarked holes for longer term storage. One of my methods is to pay extra for services so that I keep a credit on each account such as internet, power, etc... I also keep about 100 gallons of fuel with fuel stabilizer and SeaFoam.
I believe the logic is that if one has enough cash on-hand and their bank gets into trouble, they can still pay for food, fuel and other basic things to get by. It probably won't help for paying large bills like rent and mortgage unless people risk keeping a lot more cash on-hand. One can go into their brick and mortar bank to pay cash for their mortgage. It's good to do this periodically to pay extra towards the principal and shorten the loan duration.
For what it's worth, where I live (in Germany), it's usually just plain impossible to pay rent or mortgages in cash. The landlord or mortgage provider will instead use SEPA Direct Debit to pull the money out of your bank account directly. When I see a US-made movie where the landlord knocks on someone's door to collect rent in cash, it's rather bewildering. In Germany, any sentence that includes the phrase "paid rent in cash" probably starts or ends with "this is how I got scammed".
That might be the result of thinking movies bear any resemblance to reality. Approximately nobody pays rent in cash in the US, either. But movies are about telling stories, not describing how things really are.
It's not like the "don't declare income" slice of the economy disappeared.
If you're paid in cash but not declaring it, you probably want to pay rent in cash too.
Quick search, but unbanked seems a good proxy for "pay with cash": https://www.fdic.gov/analysis/household-survey/index.html
From the above, somewhere between 4.5% (average) and ~8% (low income African-American and Hispanic) people do not have a bank account.
Add in some more who choose not to declare, and it's a small but significantly non-zero number.
It very well may be. Though the last time I had to survive without a bank account, it didn't mean I paid big bills like rent using cash, it meant I got familiar with the local check cashing place and used money orders a lot. My landlords didn't want to deal with me giving them a bunch of cash every month.
At least above a certain income level if they're not paying someone off the books or maybe splitting a bill with friends/family (and even that is often some digital payment or a check) cash is increasingly uncommon. I don't think I've withdrawn money from an ATM in a couple years. And, certainly rent/mortgage, it would be almost unheard of in most situations. No one wants to be handling thousands of dollars in cash in an urban area.
You do know that not all movies represent reality, right? Iron Man, Bat Man and Spiderman do not exist, even though they're often seen in American movies.
Meanwhile in the real world of Germany, when I see the assistant at my dentist in Germany writing pacient appointments in a giant paper log-book instead of a digital calendar on a PC, it's rather bewildering.
Also bewildering, is the so called digital stuff being done through snail mail, and people paying in cash at restaurants so they can do tax fraud. Try asking them for a real receipt and not a hand written one and look at their faces.
My point is Germany is backwards in enough areas not to afford to take a high horse stance.
This only really happens in a friendly context with family or if someone is behind on rent.