It varies widely, and it depends on the specific sector and on the project. I haven't looked at ArriveCAN, so I can't comment specifically on that case.
However, as you may be aware, I've done cost estimates in a variety of sectors, including National Defence procurement, which I think I talked about at this committee. The cost estimates vary widely when comparing our institution's and some government departments'.
I'd say the capacity of government departments to provide accurate cost estimates is uneven, to be polite, and it varies widely, to be talking in plainer language.