a. If you do not currently own Bitcoin and want to own it there are many ways you can get it. They range from fast (generally more expensive) to slow (generally less expensive). Sure, if you want to buy Bitcoin on Coinbase you can do that and you will pay them a fee for that service - which I've done. You can also mine it - which I've done, be paid it in - also done, etc.
b. Secondly you are assuming that my friend can't pay for services in Bitcoin. We have both had lunch together at a restaurant in which we paid for the entire meal in BTC.
So it's an unfair statement to say my transferring of BTC to my friend costs me these fees. If you want to make the statement of "transferring USD to BTC to my friend to JPY" then sure, your statement about fees is relevant. I'm not sure suggesting that a pure BTC transfer is not an "accurate comparison" is fair.
2. See the above point. There is no trust beyond math when it come to a pure Bitcoin to Bitcoin transfer. There are plenty of things that you can buy using pure Bitcoin which I, and many of my friends, have done.