You're right, it is simple. A free society does this all the time, and has done it well before the Emergency Act. Financial institutions, from your bank to your insurance company, are required to keep track of where your payments come from. You've likely heard about the $10,000 threshold, where if someone deposits that amount at one time, they are required to notify regulators, who might launch an investigation. That's just one thing. These law exists to either prevent money laundering or other criminal activity. There are no warrants or legal judgements, just the law that requires it. And most countries have laws like this.
For financial matters, your local bank can easily freeze your account without a warrant. Hell, they do it each and every day to people across the country. It could be because of suspicious activity to prevent your savings being stolen, or because you didn't pay your service fees or make your credit card payment. The CRA can also do that if you don't pay your taxes, and can do it without a judge's approval
And shit like this happens all the time without a warrant. In the US, they have civil forfeitures. Average citizens with no evidence of a crime have seem millions of dollars confiscated by the police. Heck, the cops targeted armoured card that were collecting cash from legal marijuana shops in California and Kansas and "stealing" the cash under federal statues.
Because the continued federal prohibition of marijuana makes banks and payment processors leery of serving state-licensed cannabis suppliers, many of
reason.com
All this can happen without any court orders, warrants or legal justification. This happened before the Emergency Act. It will continue afterwards.