The core concept is being trustless. Any situation where only trusted parties are going to be present... litterally defeats the purpose. There is a lot of mechanism that is only justified in being trustless.

I could image block chain could be useful if you had digital cash off-grid, like a food truck that visited a logging camp. Collect the transactions, and then validate them when you get back to town/within signal range.

Or, any concept where the centralized trusted ledger is bulletproof, but you can't be sure that the data entered is any good. You may as well not bother with the whole thing.

Validate them when you get to town... and find that you just donated lunch to a bunch of clever loggers who knew you could not check the validity of their payments until hours after they ate the food you gave them.

You seem to have a very strange definition of "trustless."

It’s like a clearinghouses with stock shorts. You eat the few times it happens. Cost of doing business, like charge backs on credit cards.

Or you could use a standard card machine that has an included transaction buffer. I remember having these in my retail gig 15 years ago for the odd time the network went down (happened pretty much every christmas season)

So what happens when a transaction doesn't validate?

Sure where are the actual apps that are used widely?

I want more trust not less

But what do you want to trust in? Your fellow citizen? Luck in hashing?

If you wanna trust your fellow citizen: You could go down on the street and deposit your cash with strangers walking by.

If you wanna trust luck in hashing: You should be mining Bitcoin. If you are lucky, every single attempt at mining a block will be successful. You'd become rich pretty fast.