This is entirely dependent on the type of cheese being made. Famously, Parmigiano-Reggiano is required under the EU DOP scheme to be made with calf rennet.
As I say, most cheese is made with rennet enzymes produced by bacterial fermentation. Obviously, some aren't, but they are the tiniest minority. The article gives the impression that animal rennet is the norm and what I say in my comment is that it is not.
