Why is transferring money from one person to another still either slow or expensive?

You can order just about anything online and have it delivered the next day, can email anyone in the world in the course of a few minutes, and with people carrying less and less physical cash why haven’t cash transfers also become more efficient?

Services like PayPal can make a transfer internally instantly but getting that money into a bank account takes 3–4 days, and usually has some fees attached to it.

Wire transfers are faster but start out about $15 from a bank and go up from there. The process isn’t generally very easy and not widely accepted.

Neither system is really an improvement on mailing a physical check when it comes to time or expense. Are there regulations that keep person to person transfers a relatively slow process? Is there some aspect of the process that I’m missing?

As a follow up, is there a better way to make/receive cash transfers available now?