How will they sell them for cash without using an exchange and/or a bank account?

I can't just convert a bitcoin sitting in my wallet to something I can give to someone else to exchange for cash without a whole pile of guarantees.

The only people I can trade bitcoin with for cash is other bitcoin users, which - as I noted above - are few and far between.

Yes, sending BTC internationally is simpler, but that does not mean the recipient can do the same things with them as they can do with fiat, and as such it just shifts the problem to the recipient. When you send cash (using for instance western union) it is almost instantly available as well, without all the downsides of having to find someone that will trade your bitcoins at something approaching their market value.