If wallet A trusted wallet B, it would mean that the owner of wallet B would have the ability to pull tokens or currency directly from wallet A at will. In other words, the owner of wallet B would have the ability to borrow money from the owner of wallet A. The way this would work in practice is that individuals, and communities, would formally “trust” each other on a system like this (just as they do casually in the real world). That would give each other the ability to leverage each other’s capital. This web of consumer trust would allow people to directly borrow potentially large sums of money from each other in aggregate by borrowing small amounts of money from many different people. This “liquid trust” would allow for cheaper sources of financing and capital.

https://www.theinformation.com/articles/venmo-trust-and-the-blockchain