The "service" is irrelevant. I think most people would trust Porno Hub to be discreet about their visits. That's in their business interest. But now they have to tell your government about all the times you're visiting Porno Hub.
And nobody should trust their government.
Also, keep in mind that western governments share with each other. There will come a time when Australians will try to enter USA but they'll get flagged at the border because the AUS government shared that this particular individual visited Porno Hub and a few other age-restricted websites 7,000 times in the last 30 days. Red Flag!