The value to society of pot vs corn is where you should look to see why government funding doesn’t match your expectations.
But finding and better understanding its value to society is precisely what the funding is needed for.
There's plenty of value for pot in society, for some people it means they no longer are dependent on opioids for example. That being said, the Canadian government thinks this is worthy to fund, grant support for cannabis research can come from the Natural Sciences and Engineering Research Council of Canada, and because of this the bulk of the literature in recent years is published by researchers in Canadian universities.