Can not speak for Canada building codes. In the US any newer home built in the last 50 yrs if the garage has drain it must be tied to the sewage system for the reason of oil and other car related chemicals can not be dumped into the environment. If you have septic system the story could be different since getting chemical or oil into a septic system can wreck havoc on your system.
When I have seen a large square drain covers like that, it usually means there is catch in the drain, a place which sludge will collect to be cleaned out later. The actual drain is higher than the bottom of the drain box so you will always have standing water/sludge in the box. The actual drain usually goes out the side of the box or come up the middle and is 6" or so above the bottom. This done because the sewer system does not want all the dirt and salt from your car driving around in the winter. I would bail it out and see if you can find the drain pipe and see if it is cloged. I remember my dad after each winter season putting a hose down the drain pipe and running water down it to flush out any standing sludge in the drain pipe and also should have P-trap in the line somewhere to keep sewer gases from come back into the garage.
There is a down side to these type of drain, do not ever let gas or any flammable chemical get into the drain box, I seen people catch the drain on fire at minimum at worse they blow up.
If it was done correctly it should look like the picture below
