It was explained several times in the early days of things like CERB *why* there wasn't checks and balances in place - because it simply wasn't realistic. Inside the period of days millions upon millions of people got laid off across the country. If all these people who suddenly didn't have a job applied for EI the "normal way" a lot of them would have waited months for the backlog of applications to be processed. The manpower wasn't there to deal with this, and there was zero realistic way to do so in short order.
The same thing went for the wage subsidy programs and business supports. For every 1 business that abused the system, it kept thousands (likely tens, or hundreds of thousands) of others afloat. And if they made it a bureaucratic nightmare to apply and get this money millions of businesses would not be around right now leading to massive unemployment.
So the checks and balances were removed. If you applied, you got approved pretty much instantly. And you got money, sometimes in as little as 24 hours.
Yes, some chose to abuse that system, but I do have faith that it will come out in the wash when Revenue Canada starts to correlate things in the months (and yes, perhaps years) ahead. With so much in the way of payroll and banking being done electronically now everything has a paper trail - when people who applied for CERB and collected it all while their T4's showed a normal years earnings, well, there will be red flags that they will follow up on. When businesses files their taxes and show banner earnings and GST returns that don't show expected gaps, it will set off red flags.
I expect it'll take a long time for it all to come out in the wash, and I wouldn't want to work for Revenue Canada for the next 2 or 3 years as they're going to be really busy with audits and prosecutions, but I also fully expect a significant percentage of those funds will be (forcefully, or otherwise) returned.
Unfortunately, in short, this was a situation where the fears of the few could have ruined it for the many.
So they just doled out the money. Sort it out later. I think history will look at that as the right decision.