Using the new tech like Schnorr signatures is not "a complicated setup" that "has to be maintained perfectly." It is (or will be soon) built-in to the wallet software. You won't have to think about it. Maybe you read a lot about early Bitcoin wallets that didn't even provide unique addresses for each transaction (was that ever even a thing?) but times have changed. The ecosystem just gets better and better.

Also, did you read the article I linked to? In another thread I provided some more explanation and links:

All the chain analysis you have heard of is based on likely patterns and typical behavior of address use in common Bitcoin wallet software. New signature and script schemes have been added to Bitcoin in the past several years that disrupt those patterns and make it even harder to find connections between addresses.

Further reading:

https://river.com/learn/bitcoin-privacy-and-anonymity/

https://river.com/learn/what-is-taproot/

On the business transparency, you seem to completely ignore the cryptographic proof businesses can provide, that's not the same statement that businesses have been making since ancient times. It's a mathematical guarantee. All the rest you point out is true though, and so you are right that it's not a total elimination of potential fraud.