Something your generation is forgetting is that PAYING BY CHECK (like your rent, or lending or repaying money) is that you have PROOF. It is also safer to send a check through the mail than cash (which the post office strongly discourages).
One can do unlimited transactions with a checking account, but only 4 / 5 / 6 (depending) electronic transfers, payments, ATM withdrawals, etc from a savings account without being charged a fee.
People who pay by cash also risk losing it (or being robbed).
To have your wages paid into it.
To keep your money safe.
To have the use of a debit card for high street and on line purchases.
Some checking accounts give interest
To pay bills by direct deposit, which in the UK, gives a discount.
Because paying cash for everything doe snot give you a "paper trail" if one is needed. If you write a check to someone, you have the cancelled check to show that you paid the,. If you use a debit card, your bank statement will have proof as to who it was paid to. You can't track cash you use as payment, and someone could still come after you claiming you never paid them.
And if you get robbed, you lose your cash with no chance of replacing it. If you get robbed and someone steals your debit card, you just call your bank and report it stolen, and they cancel that card.
Many reasons to have one. I like having a checking account because it makes it easy for me to make transactions on large payments such as tuition and taxes.