[fruitworks]

There are techniques for anonyminity in cryptocurrency such as zero-knowedge proofs implemented in cryptocurrencies like monero and zcash (and many others)

These techniques vary in their effectiveness and efficiency. If you look at a monero transaction for example it uses something like 10x the bandwidth and CPU power to verify vs Bitcoin (which is already an inefficient network)

Some banknotes do have identifying markers, but I think you are right. Cash-like privacy should be the goal with all crypto