As others mentioned, it's not that it can be tracked, but that transactions are public by design. So yes, any on-chain transaction is out there for anyone to see. But then the matter of identifying the people or entities behind the wallets and transactions is a different issue, which largely depends on a person. If you leave your BTC address online in profiles that contain identifiable information, someone with a proper interest and enough time can figure things out. But that's not a BTC design issue and not generally an issue, unless you're severely privacy-oriented.
Bitcoin transactions are publicly seen by everyone because Bitcoin blockchain is a public one, not a private blockchain. Fortunately, with many Bitcoin transactions a day, or since 2009, how do I know that one transaction belong to who?
I can not know it, except if that sending and receiving addresses or one of them was publicly posted somewhere and was archived somewhere. If I don't have that information, I know nothing about that Bitcoin address and that Bitcoin transaction, nothing about identity of sender and receiver. It's good enough, safe enough to use Bitcoin blockchain.
Remember to use Change address, avoid reuse address, and you will have better privacy.
Privacy for Bitcoin transaction, advices.
Blockchair.com's Privacy o meter"[/url]]
General guidelines for sending BTC transactions
Blockchair can not help you improve the privacy of your
transactions but here are some basic recommendations
on how to stay anonymous on the Bitcoin network
Don't send round numbers
Don't send round amounts. Instead of sending 0.1 BTC, send 0.10125
Use Bitcoin Mixers
Mixers add an additional layer of privacy to a transaction to avoid exposing user identities.
Avoid reusing wallets
Don't send your Bitcoin change to the same address you use for sending bitcoins.
Avoid including many of your addresses in one transaction
Any time you can, try not to send BTC from your various Bitcoin addresses.
Avoid using "send everything" option
If you are withdrawing funds from an exchange, it is okay.
If you're moving funds to another wallet, do not transfer the whole amount to another address. It greatly compromises your privacy.