A wide range of occupations have drug testing. Plenty of people fail these tests. People operating heavy machinery that could kill people. Are these people's names a matter of public record? No.
But if I do test positive, or refuse to take the test, its gross misconduct, instant dismissal and a record of it throughout the industry. And my job is not at all safety critical. Footballers get "counselled"
What business is it of mine if a football player is afflited with anything?
Fair point. But, it is (or is it?) still a criminal act to consume illegal substances. You get caught, as a non-entity such as myself, you can expect your name to still be published somewhere. eg. the local paper in my home town reports the full name and street of anyone appearing in the magistrates or county court, even for minor misdemeanours where the punishment is a bond and no conviction.
Whilst you and I may not give two hoots, its a fact that by playing Australian Rules Football at the highest level, the players know that their lives become somewhat interesting to certain sections of the public. If they don't like it, they have the choice to do something else with their lives.