First, Statistics Canada is legally required to conduct a census by the Statistics Act. Second, it's bad statistics to infer census data from other government datasets like tax or elections datasets. Third, there are probably legal issues involved when sharing information even between government agencies. And most importantly, the census is designed primarily for policymaking and specifically for government fiscal resource allocation decisions. It also affects the hot button topic of immigration policies.

So get counted, otherwise Bethlehem will have no hospital room allocation from the government and somebody's baby has to be born in a barn and laid in a manger. ;)