Cash settles immediately. "Sometime in the next 24 hours" is not digital cash.

Not to mention that Bitcoin is so volatile that the transaction's value in real-world currency may be 10% higher or lower within that 24-hour window, and of course you still need to pay someone to convert it into money if you're not planning on being a crypto holder.

That's not really a fair comparison. Bitcoin cannot has very limited use for actual commerce - actually paying for stuff. So you also need to consider the inconvenience, complexity and cost of trading the received BTC for local currency.

I haven't paid anything for international transfers within the SEPA area for years. Depending on the source/destination bank, the transfer can be completed within an hour or so.

Sometimes the solution is simply better banking infrastructure. The banking/payments system in the US is a mess but it doesn't have to be so.

It really doesn't.

Bank transfers do not cost me and happen instantaneous, not 24 hours.

I can also transfer to the US, and they receive it in 24 hours. It still doesn't cost me.