Since I started hosting my game (made up of mid to late 20-year-olds) a couple of years ago we have been completely cashless. I definitely think the difference is purely generational - maybe 1 or 2 people in my player pool even carry cash. Personally, the only cash I ever carry is $20 for emergency parking or something. The OP wrote a really detailed post, but a cashless game doesn't have to be complicated at all. Granted, I don't do credit. This is how I do it:
1) As players arrive they simply send a payment for however much they want to buy in for. When I get a notification on my phone that the money is received (instantaneous) I count out the chips, just like if they had paid cash.
2) End of the night everyone counts up, I check the total payout against the total buy-ins, if it matches (9 times out of 10) we're golden and I send everyone their winnings.
3) When it doesn't match everyone recounts and, if necessary, I can count people's stacks too. Never not had it come out even.
We exclusively use Venmo. All the funds are aggregated in one place and the nice thing about Venmo is that you can pay from your balance. I'm usually a winning player, so 3 times out of 4 I don't even have to transfer anything to my bank/card. People can do no notes or (more often) they write something completely unrelated or wildly inappropriate for fun. I just tell them not to write poker/gambling/etc. and it's never a problem.
I think cashless also works well for our microstakes so we don't have to mess with coins. Maybe if we had a $1/$1 or $1/$2 game cash would be easier, but it's actually easier for us to be cashless.
Just a lowly millenial's opinion!