Most transactions are through a bank. Because banks have to comply with KYC (Know Your Customer) they have access to all transactions with a search warrant for ALL accounts.

There are many stories of peoples accounts being frozen for 'suspicious' activity. I don't think this is the norm. BUT it can be done with the current system in place.

The IRS can take money from accounts, and garnish wages. BUT I think it's quite rare - maybe getting more so but still very rare.

The idea these systems are in place are beyond comprehension to me - why Bitcoin wins with me.