From a customer's perspective, credit cards are also "free". However, from a merchant's perspective, the cost is 2-3% plus a constant hassle with prospective fraud.

Traditional wire transfer certainly cannot, since the fees alone are many times larger than $1 USD.

The international small amount transfer use-case is extremely rare and unlikely to take-off because of Libra.

In any case, you seem to be assuming Libra won't charge forex fees for converting between Libra and fiat currency. They have not said so. It is very likely they will charge.

I don't see any reason why the banks involved in exchanging Libra with fiat currency to behave any differently than they do today. They will play with the buy/sell rates to make money on both sides of the trade.