When sampling is more appropriate than a census?

Yes.

A sample only provides data from some of the population and is then extrapolated to the whole population; this assumes that the sample is taken equally from all possible datum points across the population - this cannot be guaranteed.

A census provides data from all of the population so it is 100% as accurate as the data reading - whether the data collected is accurate or not depends upon what the data is and how it is obtained.