Yes, if people are using services like Coinbase to purchase cryptocurrency and/or transfer funds to their bank account etc., then they will be flagged once their Coinbase account sees 20k or more of transfers and their information will be handed over to the IRS for auditing purposes.
The IRS hired a software company to developed a program that can scan crypto addresses to see if you are trying to hide anything.
That said, there /are/ tumblers, stealth addresses, dark wallets and other ways to obfuscate transactions, should you choose to go that route.
Sites like localbitcoins allow peer-to-peer buying/selling of crypto without the need for a bank account, but you will likely pay a premium.
There are many ways to trade anonymously, whether you want to trade crypto or FX.