In other words, wire transfers are both more desirable and easier to steal than physical goods, and once stolen are unrecoverable. And they don’t want to process them so they keep the cost as high as possible.
The cost of wire transfers is due to the insurance cost of theft by retailers. Imagine instead that the post office shipped and delivered envelopes of money, and how the behavior of the post office would change.
That is why it is cheaper to send hard-to-exchange goods, than exchange goods. And why it is more cost effective to steal money than stuff you have to sell or pawn.
This is why Bitcoin (BTC) are better and cheaper means of wire transfers. The intermediaries in the chain of handling are not exposed to risk – just you.
Everyone argues that BTC is helpful for the high end of the market, and I totally disagree. The primary virtue of BTC is in its application to solutions for the poor – who pay high costs because the marginal value of each unit of currency is more expensive for them than for everyone else.