It's not the cryptocurrency itself that prevents fraud, it's the surrounding technologies such as blockchains and NFTs.
Using NFT to own the address to a PNG is hilariously stupid and worthless, but what it's actually great for is receipts. If I buy a donut and get an NFT proving that I now own the donut (along with metadata about where and when I purchased the donut) and months later I am on trial for murder, I can prove to the court with absolute mathematical certainty that I couldn't have killed anyone at that time because I was eating a donut halfway across town.
Using blockchain similarly is great for proving your transaction history. Maybe I somehow faked that NFT about the donut? Well, I couldn't have, because it was months ago and blockchain history is cryptographically impossible to spoof.
These are obviously contrived examples, but when applied at scale it becomes an extremely powerful way to verify truth. Yes, I did in fact buy those tickets, here's my NFT, now let me on the plane. No, I did not spend $3000 on knock-off accessories, here is my blockchain. The odds of someone being able to fake these is extremely low.
But, again, this will never come into practice, at least not in the near future. As @beefcat pointed out, implementing these systems would be expensive for the established financial institutions, and would present new challenges for them to create new processes for handling. An awful lot of work to create something that is stronger and safer when there is little motivation for them to do so.